Add an additional argument to the main function: 'parameters' (dict/hstore)
Mode Standalone: add parameter '-p/--parameters' for parameters
Eval: new function 'parameter'
Language support: set 'lang' parameter

- at compile time get default language from locale
- in standalone mode get current language from locale
Eval: new function 'lang'
Eval: enable tests with new parameters; add an "English" name
Eval: new function 'localized_tag'
Type 'tag_value': language support for value 'auto'

- closes #53
Main / Mode Standalone: new parameter --lang to choose language
Pseudo Classes: pseudo classes may accept a parameter
Pseudo Classes: implement :lang()

- closes #16
Document language support
Merge pull request #72 from plepe/parameters-and-language-support

Parameters and language support