#1 %EXT_FILTER extensions are case sensitive

[Sam Bryan]

( This is certainly the case with v3.31 - I can't see any fix listed in the changelog for 3.37, but it doesn't look like I'll get the opportunity to actually test the new version properly. )

The %EXT_FILTER array (in conf.pl) appears to be case sensitive - e.g. "myname.doc" will be passed to the specified external filter program, but "myname.DOC" will not.

lowercasing the suffix prior to the return in get_suffix() (tools.pl) seems to resolve this.