Merge pull request #99 from ngbrown/issue_98

Fixes ofxCv::RectTracker::track() to erase from map directly with iterator and stop re-using iterator.
Merge pull request #100 from ngbrown/of8_update_for_vs

Update Visual Studio solutions to OpenFramework 0.8.0 paths.
This should fix issue #101 by post-incrementing the iterator before erasing and not relying on map::erase returining a value.  This should also resolve merge request #102 because there are no defines and no invalid iterators.