[Feature] db_commit plugin allows a more verbose commit
prints logf messages to the screen buffer and dumps the
output to .rockbox/db_commit_log.txt
logs warnings about tags that can't
be displayed by the current font
adds an option to the tagcache using the file
.rockbox/database_commit.ignore to prevent auto commit
Change-Id: Ib381b3b6d9dd19d76c95d0e87e605f7378e29674