MapCSS: Disable rules with pseudo classes
Eval: implement missing eval functions

- rename number() to metric()
- MapCSS 0.2 functions: int, num, metric, zmetric (not done, just a template),
  str
- further functions: round
Eval: some functions only accept int as parameter (get, set, round)
Eval:: +, -, *, /, sqrt: convert none to 0
Eval::div: bugfix
MapCSS: @default_other -> default values of other properties
Default Base-Style: @default_other properties
Parse Eval: operators that are not in regexp; '.' concatenates strings
Parse Eval: parse explicitly positive/negative values