This commit cleanups codestyle a bit, yet there is still some work to be done

This adds support to list global and per mount roles on stats.xsl.
This isn't nicest formated but works.
This also adds <source>-like <authentication> with <role>s to
root node.
Closes: #2133

Add '?omode=legacy' to any URI or <resource ... omode="legacy" />.
Please test.
closes #2097

svn path=/icecast/trunk/icecast/; revision=19376

This patch *replaces* the authentication system completly.

What is new:
 - <authentication> in mount section is now a container object.
 - <authentication> in root and mount section may hold any number of <role>-Tags.
 - <role> tags:
   Those tags define a 'role' and it's ACL rules.
   A role is a instance of an authentication module (see below).
   <role> takes the following options. All but type are optional.
   - authentication related:
     - type: Type of the authentication module (values: anonymous, static, legacy-password, url or htpasswd;
             symbolic constants in auth.h)
     - name: Name for the role. For later matching. (values: any string; default: (none))
     - method: This rule is only active on the given list of HTTP methods.
               (list of enum values: methods as recognized by httpp/ (e.g: get,post); default: *)
   - ACL related:
     - allow-method: Allowed HTTP methods.
       (list of enum values: methods as recognized by httpp/ (e.g: get,post); default: get)
     - deny-method: Rejected HTTP methods.
       (list of enum values: methods as recognized by httpp/ (e.g: get,post); default: *)
     - allow-admin: Allowed admin commands. (list of enum values: admin command; default: buildm3u)
     - deny-admin: Rejected admin commands. (list of enum values: admin command; default: *)
     - allow-web: Allowed web pages. (values: empty or *; default: *)
     - deny-web: Rejected web pages. (values: empty or *; default: (empty))
     - connections-per-user: maximum number of simultaneous connections per role and username.
       This is only active on active sources.  (values: unlimited or number of connections; default: unlimited)
     - connection-duration: maximum time of a connection. This is only active on active sources.
       (values: unlimited or number of secounds; default: unlimited)
   <role> takes <option> child tags. <option> tags contain a name and a value option.
   Meaning of <option> tags is up to the authentication module.
 - <role>s are considered to build a stack. If a role returns with AUTH_NOMATCH the next one will be tried.
 - <role>s are tested in this order: mount specific, default mount specific, global, internal fallback.
   Internal fallback is set to allow web/ access via GET, POST and HEAD (only GET supported by this time)
   and rejects all other requests.
 - New authentication module: anonymous
   This module matches all requests. No options taken.
 - New authentication module: static
   This module matches with a static username and password.
   It takes two <option>s. One with name="username" and one with name="password" to set username and password.
   This replaces old style <*-username> and <*-password> tags.
 - New authentication module: legacy-password
   This module matches with a statich password.
   It takes one <option> with name="password" to set password.
   This replaces old ICE and ICY (shoutcast compat mode) authentication.
 - Parsing <authentication> in <mount> with a type set in a special way to allow 100% backward compatibility.
 - Parsing of <source-password>, <admin-password>, <admin-user>, <relay-password> and <relay-user> in global
   <authentication> for 100% backward compatibility.
 - <alias> is now proccessed very early. This enables them to be used for all kinds of requests.

To Do List & What does not yet work:
 - type="url" auth: mount_add and mount_remove.
   This should be replaced by an unique feature I would call '<event>'.
 - Admin commands manageauth and manageauth.xsl are disabled as they need more review:
   This code needs to be ported to support multiple <role>s per <mount>.
 - url authentication module can not yet return AUTH_NOMATCH.
   This needs to be reviewed and discussed on how to handle this case best way.
 - Default config files needs to be updated to reflect the changes.
   As this is quite some political act it should be done in dicussion with the whole team
   and permission of the release manager.
 - Docs need to be updated to reflect the changes.

How does it work:
 Code has been changed so that authentification is done early for all clients.
 This allows accessing the ACL data (client->acl) from nearly everywhere in the code.

 After accept() and initial client setup the request is parsed. In the next step
 all <alias>es are resolved. After this the client is passed for authentication.
 After authentication it is passed to the corresponding subsystem depending on kind of request.

 All authentication instances have a thread running for doing the authentication.
 This thread works on a queue of clients.

Hints for testers:
 - Test with default config.
 - Test with diffrent authentication modules in <mount>.
 - Test shoutcast compatibility mode.
 - Test with new style <authentication> and any amount of <role> (zero to quite some).
 - Test <alias> lookup on all kinds of objects.
 - Test source level credential login into the admin interface.
 - Test shoucast style meta data updates.
 - Test playlist generation.

Thank you for reading this long commit message. Have fun reading the full patch!

svn path=/icecast/trunk/icecast/; revision=19358

some more changes for ACL framework: exported admin_get_command() and ADMIN_COMMAND_ERROR as well as introduced ADMIN_COMMAND_ANY

svn path=/icecast/trunk/icecast/; revision=19349

svn path=/icecast/trunk/icecast/; revision=19343

svn path=/icecast/trunk/icecast/; revision=13559

one. The generated one comes from an xslt in adminroot. Just need some icons

svn path=/icecast/trunk/icecast/; revision=13539

svn path=/trunk/httpp/; revision=5792

rename util_url_escape to util_url_unescape, and write a util_escape function
that actually DOES escape things. Fix all the callers of the function to call
the correct one of these two.

svn path=/trunk/icecast/; revision=4414