Integration of fixed point sub-functions 17.

[x] Few sub-funcs of ivas_dirac_dec_render converted to fixed point
[x] Few float structure elements and buffers clean up
[x] Fix for issue#726
[x] Removal of some of the intermediate conversions
[x] Integrated TDREND_GetMix function in external Renderer
[x] stereo_dtf_cng fixed point implemented
[x] Integration of ivas_mdct_core_reconstruct function inside mct_dec path.
[x] Fix for issue#731
[x] Add conversion for ivas_param_mc_dec_reconfig