Mark _BitScanReverse as an intrinsic, as this is not done by default
 in _DEBUG mode (thanks to Bjoern D. Rasmussen for the suggestion).
Move the declaration of ec_ilog() to where the macro using it is
 defined, to ensure it is available when the macro is used.
Thanks to John Ridges for the report.

The return code has been eliminated in favor of using the existing
 error flag in the ec_enc struct.
This also adds the declaration to the header, which JM's importation
 of Koen's adaptation of my original code in b3c05b6b omitted.

Correct a number of uninitialized value problems when end!=nbEBands. Now 8khz/20ms audio can be decoded at 48kHz and vice versa (with the PF turned off).

Change the bit-stream (without causing desync)

Got authorization from all copyright holders

CELT_SET_END_BAND_REQUEST in the decoder was performing the wrong bounds check and not allowing a change to fullband.

This fixes a number of issues for platforms with a 16-bit int, but
 by no means all of them.
The type change for ec_window (for platforms where sizeof(size_t)==2)
 will break ABI (but not API) compatibility with libsilk and libopus,
 and reduce speed on x86-64, but allows the code to work in real-mode
 DOS without using the huge memory model, which is useful for testing
 16-bit int compliance.

Though the encoder will still never use more than 1275 bytes

1275 byte packets is the absolute maximum packet size we're going to support. This makes the encoder and decoder refuse to operate outside of these boundaries.

Also cap the encoder bit-rate to 260 kb/s per channel.

Also properly applies the MDCT filtering for resampling

Not after.

This fixes the frame_size check on the encoder and decoder and removes some unused variable warnings when compiling without custom modes.

This unifies the byte buffer, encoder, and decoder into a single
 struct.
The common encoder and decoder functions (such as ec_tell()) can
 operate on either one, simplifying code which uses both.
The precision argument to ec_tell() has been removed.
It now comes in two precisions:
  ec_tell() gives 1 bit precision in two operations, and
  ec_tell_frac() gives 1/8th bit precision in... somewhat more.
ec_{enc|dec}_bit_prob() were removed (they are no longer needed).
Some of the byte buffer access functions were made static and
 removed from the cross-module API.
All of the code in rangeenc.c and rangedec.c was merged into
 entenc.c and entdec.c, respectively, as we are no longer
 considering alternative backends.
rangeenc.c and rangede.c have been removed entirely.

This passes make check, after disabling the modes that we removed
 support for in cf5d3a8c.