interactive debugger inside pythonista editor

##features

• single stepping, step over, step out
• continue, or quit
• stack up, or stack down
• watch window (view only right now)
• During debugging, current line is highlighted, and editor opens new file if needed
• Stack up/ down buttons
• Create edit menu action to start debugging current script. Point to vdb.py with no arguments to run/debug script, use pm as argument to start post mortem of last traceback.
• Locals window has some primitave capability to modify variables : sequences, dicts, modules, many classes are supported. Value changed must be eval-able. Currently window does not update

##TODO:

• breakpoint set/clear by tapping line #s
• help menu
• optimizations for small devices

	import vdb
	vdb.set_trace()

In addition, the following will begin debugging at the last traceback.

	import vdb
	vdb.pm()

##install Thanks to @ywangd for this method.

import requests as r; exec r.get('https://github.com/jsbain/vdb/blob/master/get-vdb.py').text