Also evaluate if-not-content.

However, we are at risk of replicating apply-conditions.xsl in it's
entirety. this needs refactoring.
Merge branch 'master' of git://github.com/plone/diazo

Conflicts:
	docs/CHANGES.txt
Add TODOs for debugger
Merge remote-tracking branch 'plone/master'

Conflicts:
	docs/CHANGES.txt
	lib/diazo/tests/test_trace.py
Merge pull request #13 from lentinj/master

Also evaluate if-not-content.