Rename final function to pgmapcss_{style_id}()
Parse Condition: bugfix, expecting ]
Bugfix: when working with bbox null, use 'None' as geometry (not '')
Eval::min(), max(): bugfix (ignore empty values)
Parse Condition: bugfix, expecting ]
Bugfix: when working with bbox null, use 'None' as geometry (not '')
Always pass stat to compile_eval()

- Bugfix 7de251e44f30615b26a93e0cbdd12be0f67d508d
Eval::min(), max(): Bugfix, really convert values via metric()
Merge branch 'branch-0.6'

Conflicts:
	pgmapcss/parser/parse_condition.py
Compile condition: < > <= =>: use eval_gt() (or similar) functions
Example combined_roads: improve

- define zoom levels
- add motorways and trunk roads
- use hex color values
- combine only roads with a name
- print labels on layer 10