Antimony 0.7.3

Features:

• User-defined script nodes are now auto-populated into Add menu. They are stored in the nodes folder and categorized by subfolder.
• Optional third argument for input in scripts; it sets the starting value.
• Open files from the command-line with antimony $FILENAME.sb
• make install copies Antimony and sb data directory into /usr/local/bin (Linux only)
• Double-clicking a .sb file will open it in Antimony (Mac only)

Bugfixes:

• Fixed crash when loading files that contain connections.
• Fixed frequent crashes caused by reference counting on Py_None object.
• Change deletion of rendered images to fix strange crash.
• Fixed crash caused by loading file with Python errors.