Script to auto-generate processing.vim syntax file from keywords.txt

Hi Erich,

I see there is currently an issue, #9, relating to missing keywords in the syntax file. This pull request is my attempt to address that issue by using a python script to auto-generate the syntax file, based on the keywords.txt file supplied with Processing 2.0.1.

There are a few things included in the request:
 1. `make_syntax.py` - The syntax file generator script, which takes keywords.txt as an argument. Run it with `-h` for a usage summary.
 2. `syntax.tmpl` - A template for the syntax file. Keywords are extracted from `keywords.txt` and substituted into this template.
 3. `compare.py` - A script to extract keywords from two different Vim syntax files, showing which keywords have been added to, and which keywords have been removed in the second file. I made this because diff wasn't very useful for comparing two syntax files.
 4. `processing.vim` - A new syntax file based on the output from `make_syntax.py`. Check the log for the [most recent commit](https://github.com/vortura/vim-processing/commit/81cbc36950866e10a1399858e33da14f80f794a1) for the output of compare.py, which shows what has changed.

I hope this is useful. Let me know if you have any questions, or if you'd like to see anything changed.