SILK fixes following last codec WG meeting

decoder:
- fixed incorrect scaling of filter states for the smallest quantization
  step sizes
- NLSF2A now limits the prediction gain of LPC filters

encoder:
- increased damping of LTP coefficients in LTP analysis
- increased white noise fraction in noise shaping LPC analysis
- introduced maximum total prediction gain.  Used by Burg's method to
  exit early if prediction gain is exceeded.  This improves packet
  loss robustness and numerical robustness in Burg's method
- Prefiltered signal is now in int32 Q10 domain, from int16 Q0
- Increased max number of iterations in CBR gain control loop from 5 to 6
- Removed useless code from LTP scaling control
- Optimization: smarter LPC loop unrolling
- Switched default win32 compile mode to be floating-point

resampler:
- made resampler have constant delay of 0.75 ms; removed delay
  compensation from silk code.
- removed obsolete table entries (~850 Bytes)
- increased downsampling filter order from 16 to 18/24/36 (depending on
  frequency ratio)
- reoptimized filter coefficients

silk/tuning_parameters.h

@@ -51,13 +51,11 @@ extern "C"
 /*********************/
 
 /* LPC analysis defines: regularization and bandwidth expansion */
-#define FIND_LPC_COND_FAC                               2.5e-5f
-#define FIND_LPC_CHIRP                                  0.99995f
-#define FIND_LPC_CHIRP_FIRST_FRAME                      0.96f
+#define FIND_LPC_COND_FAC                               1e-5f
 
 /* LTP analysis defines */
 #define FIND_LTP_COND_FAC                               1e-5f
-#define LTP_DAMPING                                     0.01f
+#define LTP_DAMPING                                     0.05f
 #define LTP_SMOOTHING                                   0.1f
 
 /* LTP quantization settings */
@@ -108,7 +106,7 @@ extern "C"
 #define WARPING_MULTIPLIER                              0.015f
 
 /* fraction added to first autocorrelation value */
-#define SHAPE_WHITE_NOISE_FRACTION                      1e-5f
+#define SHAPE_WHITE_NOISE_FRACTION                      5e-5f
 
 /* noise shaping filter chirp factor */
 #define BANDWIDTH_EXPANSION                             0.95f