Added an interface to encode/decode from a CELT range coder

interface/SKP_Silk_SDK_API.h

src_FLP/SKP_Silk_encode_frame_FLP.c

src_FLP/SKP_Silk_main_FLP.h

src_common/SKP_Silk_code_signs.c

src_common/SKP_Silk_dec_SDK_API.c

src_common/SKP_Silk_decode_frame.c

src_common/SKP_Silk_decode_indices.c

src_common/SKP_Silk_decode_parameters.c

src_common/SKP_Silk_decode_pulses.c

src_common/SKP_Silk_enc_API.c

src_common/SKP_Silk_encode_parameters.c

src_common/SKP_Silk_encode_pulses.c

src_common/SKP_Silk_main.h

src_common/SKP_Silk_range_coder.c

src_common/SKP_Silk_shell_coder.c

src_common/SKP_Silk_structs.h

src_common/SKP_Silk_tables.h

src_common/SKP_Silk_tables_other.c

src_common/Silk_CommonFLP.vcproj

test/Dec_SDK.vcproj