URL-escaping ?=& in the mountpoint prevents mountpoints with query strings

#11b83da8 breaks connecting to mountpoints with a query string.

We are running a libshout compatible streaming server (at least we try ;) ) which uses a query string parameter to set a priority for a source client. This way a newly connecting source client can auto-kick an existing source client by providing a higher priority. I only now realized that by updating from my old libshout 2.3.1 on debian to 2.4.3 on ubuntu query string get now escaped:

SOURCE /m1?prio=3     HTTP/1.0  "ices/0.4 libshout/2.3.1"
SOURCE /m1%3fprio%3d3 HTTP/1.0  "ices/0.4 libshout/2.4.3"

I realize that the exact semantics of "mountpoints" aren't formaly specified (or are they?) but this completely broke my expectation of a mount point basically just being the path of a URL.

I opened an issue on github before I found the repo here. I'm gonna close over there and refer to this issue here.