Don't sort cues in a bogus way
Cues rendering: reset num of processed cue entries when creating a new file
mm_mem_io_c: get_buffer() for r/w instances
Helper function for writing an EBML element's head (ID + size fields)
mkvmerge: store cues in a normal vector instead of KaxCues

Means a huge decrease in memory usage. Fixes #871.
mkvmerge: sort cue entries
ChangeLog update