bin/go: Rewrite in perl

Also deal with when it appears multiple times in the PATH.
.gitconfig: Don't use diff3
.gitexcludes: Ignore .tags*
.mpv/config: Update settings

Add wasapi as the preferred AO (instead of oss in cygwin).

Change cache to the new cache-default option, which avoids the cache
indirection when accessing local files.

Add lua suboption for the lua_experiment branch with a modified version
of the osc.lua. Set osd-font to Meiryo to match the font used in the
osc.lua.
Update submodules