Avoids conflict with LPCNet, so that LPCNet headers can be included in
Opus

Larger network, using 8-bit weights

Based on two dense layers with a GRU layer in the middle

- celt/modes.c:430:14: warning: cast from 'const unsigned char *' to
  'opus_int16 *' increases required alignment from 1 to 2 [-Wcast-align]
- 'C[0][1]' may be used uninitialized [-Wmaybe-uninitialized]
- Unused variable/parameter
- Value stored is never read
- MSVC warnings about "possible loss of data" due to type conversions
- MSVC warning C4146: unary minus operator applied to unsigned type
- silk/NLSF_del_dec_quant.c:137:20: warning: array subscript is above
  array bounds [-Warray-bounds] (gcc -O3 false positive)
- src/mlp_train.h:39:20: warning: function declaration isn't a prototype
  [-Wstrict-prototypes]
- Remove SMALL_FOOTPRINT code from SSE 4.1 FIR implementation, matching
  the C implementation.

The clang -Wcast-align warnings with SSE intrinsics are a known
clang issue: https://llvm.org/bugs/show_bug.cgi?id=20670

The change also makes the analysis run for sampling rates of 16 kHz and 24 kHz
since the features are only computed on the 0-8 kHz band. The longer time
window (20 ms instead of 10 ms) makes the tonality estimator more reliable
for low-pitch harmonics.

New MLP doesn't attempt to classify silence as speech/music

Avoids biasing the decision when it's all silence/noise.

Fixes an MSVC double truncation warning.

Also, reducing the VBR rate on panned mono