fixed NPE on cut in empty file
do not allow to completely remove cells from notebook
fixed switching between cell types
do not resize cells on re-add first cell to the file
added commons-io to the ipnb
default values for nbformat and metadata in raw ipython file
cleanup, add class name to exception message
add first cell if ipynb file is empty
Merge remote-tracking branch 'origin/master'
IDEA-130994 Settings: Editor | Colors & Fonts | Diff — cosmetic issues
IDEA-129339: show tracked branches in general "remote/..." groups