GOP-PROP 1a: python formatting

[Graham Percival]

We are no longer going to rush this item; the schedule has been
adjusted accordingly:
http://lilypond.org/~graham/gop/index.html

Corrected proposal, copied from:
http://lilypond.org/~graham/gop/gop_1.html


Proposal: let’s follow the indentation described in PEP-8.
http://www.python.org/dev/peps/pep-0008/

    * use 4 spaces per indentation level
    * never mix tabs and spaces (for indentation)
    * Code indented with a mixture of tabs and spaces should be
      converted to using spaces exclusively 

There should be absolutely no tab characters for indentation in
any .py file in lilypond git. All such files should be converted
to use spaces only. You can see such files with
        

address@hidden:~/src/lilypond$ git grep -l $'\t' -- "*.py"
python/convertrules.py
python/fontextract.py
python/lilylib.py
python/musicxml.py
python/rational.py
scripts/auxiliar/makelsr.py
scripts/build/create-weblinks-itexi.py
scripts/build/website_post.py
scripts/musicxml2ly.py

Rationale: mixing indentation styles is not a great idea, and in
my experience of python code documentation and examples online,
the 4-space indent rule from PEP-8 is almost universally followed. 


Cheers,
- Graham