fix pcm_seek() to inline
fix vcxproj
fix warning: cast size_t as sprintf() arg to int
fix unused variable warning
smart padding for better gapless playback

Taken smart padding code using LPC extrapolation from vorbis/opus.
Padding is done on both beginning and ending, but enc_delay and padding
remains the same (we discard extra padding frame introduced on our side
after encoding).
add some copyright notice
cleanup interface of aac_encode_frame()
prepend 1 sample zero padding in case of SBR and enc_delay is odd

This is required because odd enc_delay cannot be exactly expressed in
downsampled scale, and HE-AACv2 FDK encoder actually has odd enc_delay.
rename aacenc_result_t -> aacenc_frame_t, simplify write_sample()
use tell() to obtain data chunk offset
bump version
update ChangeLog