[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

apps/plugins/SOURCES

@@ -4,6 +4,7 @@ battery_bench.c
 #endif
 #ifdef HAVE_TAGCACHE
 db_folder_select.c
+tagcache/tagcache.c
 #endif
 chessclock.c
 credits.c