This patch adds partial support for profiling through Cocoon pipelines.
You still need to replace the /standard pipes/ with the /profiling pipes/ in
The profiling results can be accessed via http://localhost:8888/profile.html
during "forrest run".
Note that you need to load a page first, to get some profiling data.
Also note that after this change "profile.html" is reserved for the profiling page. This will
go away after step 1 below, I guess.
Next steps probably are:
1) Refactor profiler.xmap into a (output) plugin, probably including a profile2document stylesheet
2) Find out how to automatically replace the pipes with their profiling counterparts
3) Find out how to best get some "profile.html" during static site generation