Reduced visibility of ocl collection internals.
Removed dead comments.
Minor fixes.
OPEN - task 10: Traversal strategy for visiting commits 
http://github.com/markus1978/srcrepo/issues/issue/10

Implemented new visiting code. But Java importer does not react to new
branching and merging callbacks yet.
Fixed issues with checkout conflicts. Problem is/was, that sometimes the
stage is dirty and git will not checkout a different rev. Call now reset
--hard first.
OPEN - task 10: Traversal strategy for visiting commits 
http://github.com/markus1978/srcrepo/issues/issue/10

Only import the first encountered branch for now. 
Fix: non java projects do not cause the wrong error anymore.
Fix: Refresh the project structure after the project structure was
updated due to changes .project files.
Fix: use git clean in addition to reset the clean the working directory
before checking out a new commit.
OPEN - task 10: Traversal strategy for visiting commits 
http://github.com/markus1978/srcrepo/issues/issue/10

Improved on git checkout command for less conflicts during checking out
revisions.
Ignoring .cache files.
Configurable EMF-Frag cache size.
Reaction to latest minor API changes of emffrag.