codeparser: add module for parsing shell/python

codeparser: add module for parsing shell/python

This commit is derived from Chris Larson's checksum work, turned into a
standalone piece of code for parsing python and shell functions.

The deindent code has been replaced with code to work around indentation
for speed. The original NodeVisitor in the ast was replaced with a faster
class walk call.

Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>