Move data type pgmapcss_rule_properties to types.sql (and rename from pgmapcss_properties_return)
Type pgmapcss_rule_properties: rename prop_list to prop_types
'where' Selectors: all selectors that make an object show
pgmapcss_compile_conditions(): compile an array of conditions
pgmapcss_compile_where(): return where clauses necessary for showing objects
objects(): use where clauses for index usage
objects(): speed up db queries by using multicolumn indexes
split pgmapcss_parse_content() from pgmapcss_compile_content()

- save all selectors and resulting properties in pgmapcss_compile_stat
pgmapcss_compile_where(): include implicit objects from set-statements
pgmapcss_build_statement(): some statements are only needed for eval-statements
pgmapcss_compile_where() fix
Preprocess test-template.mapnik: generate rules for all used colors in css-file
Eval::eval_any(): return first non-null value
Eval::eval_number(): bugfix, accept negative values
doc/API: convert file to markdown syntax
doc/API: Improve documentation _result, _check
doc/API: add documentation for {style_id}_match()
Eval: define available operators in table 'eval_operators'
Eval: add ==, != (and <>)
Eval: Add a couple of functions handling lists