closes #6, fixing breakstrand bug
fixes #7, tooltips added
fixes #8, closes #8
fixed: slice view partially cut off
pencil tool now uses part.createXover
automatic stage adjustments after browser window is resized
undo redo with crossovers done partially, until implementation of multiple undo/redo commands is complete #3
fixes #10, fixes #11
added some comments
(partially done) pencil tool for strands
skip insert items added to model
code cleanup
merged sam-aug13 and sudhanshu-aug13 branches