[FEATURE] added script to set up python virtual environment
moved initialisation of virtual environments to a common place
[FEATURE] added script to batch extension change
default behaviour without arguments is to rename jars to zip
[DOC] commented change_extension.sh
[FEATURE] added git-merge shortcut
Merge commit 'f199c0778ab68929484ca799b70b0bee242f8c1a' into develop