Implement a file filter similar to URL filter.

An updated version of the patch by Adam Treat <treat@kde.org>:
    Implement a new file filter using POSIX Portable Filename Character
    Set along with KDE's mimetype database of file extension blobs that
    filters text matching a POSIX portable pathname and underlines it
    very much like links.

REVIEW: 128241
REVIEW: 114376