replace boolean conditional checks on possibly uninitialized vars with \!empty/empty/isset as appropriate

Removed extraneous whitespace to eliminate errors reported by the
Squiz.WhiteSpace.SuperfluousWhitespace sniff.

The old 'default' template was deprecated with the release of the new
'dokuwiki' template (2012-10-13). It is still available in a separate
repository here: https://github.com/dokufreaks/template-default

But no-one in the core development team intends to maintain this template
anymore. So, anyone willing to adopt it is welcome to clone it and make it
your own.

Fix violations for Zend.Files.ClosingTag.NotAllowed

Added the pointer icon to the media manager pop-up to show users it is clickable.

For Ingo from the LinuxHotel

less will use the right one based on parameter counts

also made it more secure against copy'n'paste

This adds a custom event to the 'dokuwiki' template that allows plugin
authors to easily integrate custom pagetool buttons into the template.

This reverts commit 37764cbb.

This fixes the image display in IE7 with the disadvantage that now in
IE7 with images disabled the text won't be displayed anymore.

This makes the pagetools in non-hover/static/active-mode use another
image replacement technique that falls back to the text when images are
disabled. Furthermore this fixes the :focused-display in IE7 by using
:active, too.