ParseFile() either accepts a filename or content

- parse_file() has the same distinction
- move request for mapnik base style mapcss from ParseFile to parse_file()
- rename argument 'file' to 'filename'
- error-message: differentiate between <string> and filename
ParseFile: add function seek()
parse value/eval: fix parsing eval statements consisting/starting of a string
eval_lighten(): bugfix
DB functions update: print filename before installing to db
Versioning: update to 0.6-dev
Merge branch 'branch-0.5'