setting version for dev release

SDL release 2.524

SDL-2.524_1 testing for t/mixer_channels.t failures

Version 2.523

Updated to 2.520_3

Didn't perform manifest before releasing SDL 2.520_1. New release at …

…2.520_2

Development release 2.520_1

version 2.518

Please don't use -T

Iterated to 2.514, dude to feature additions + stability