"Myrkwid"s majore rewrite of internals

API should be unchanged, beside some extras delivered

Should meet bug fixing goal of Milestone "Myrkwid"

Functions moving point centered around 
`py-beginning-of-statement', `py-end-of-statement'

with `py-travel-current-indent' core stepping downwards.

Also `py-compute-indentation' redone.

Enjoy!