#19 Add Per-Item Keyword Searching

[Morbus Iff]

This is already possible with a little bit of template
editing, but there should be a "keyword search" feature
in AmphetaDesk, where a user would type in a regex
under the "My Settings" page, choose a method of
notification (background color, move-to-top, stronger
text, etc.), and then each feed item would be checked
against this regex. Largely, only a front-end would
need to be made, as well as something like:

my $regexp = get_setting("item_regexp");
item_notify if $item->{description} =~ /$regexp/;