KEGG KGML parsing and graphics with tests

(Single commit combined from Leighton's branch by Peter,
removing accidentally committed files and test output files)
Use standard online check in test_KGML_online.py

This avoids code duplication, but also is essential for
the run_tests.py --offline switch to work as intended.
Use system temp folder for downloaded file
Check for PIL in test_KGML_graphics.py
Use system temp folder for output files
Write sample PDF output from KGML to Graphics folder
Use the official KEGG REST API's URL to get KGML files
Fix with statement on Python 2.5; removed unused import
Remove unused ReportLab import which was breaking unit test.

This import meant test_KGML_nographics.py failed when run
without ReportLab. The import appears to be unused anyway.
KEGG update - Fix misc Python 3 problems

When the original branch was written, I think we still used 2to3.
Suggest Pillow rather than PIL for bitmap graphics tests
NEWS entry for parsing, representing & drawing KGML pathways
KGML tweaks: PEP8 docstring formatting; colour --> color
Make KGML pathway property get/set/del helper methods private