Allow button modifiers in url-select

Almost verbatim copy from matcher.
Removed .gitignore
Nicer living
Abort keyboard & url selection modes with Ctrl-c; fixes issue #46
url-select: New default regex, fixes issue #47
Added ~/.urxvt/ext install location to README
url-select: fixed underlining of URLs, fixes issue #47
copy from 'matcher'. allow comments and spaces in patterns
matcher.pattern. starts from 0
implement incremental search

Fix muennich/urxvt-perls#51
url-select: catch button presses, fixes issue #54
Merge remote-tracking branch 'upstream/master'