Improved the skin reader and updater in vndb.pl
Improved the skin reader and updater in vndb.pl

Less error prone, and only updates the skins that need updating and
are actually writable.

morkt/vndb,morkt/vndb,erengy/vndb,christian-roggia/vndb,christian-roggia/vndb,morkt/vndb,morkt/vndb,christian-roggia/vndb,morkt/vndb,erengy/vndb,erengy/vndb