Improvments to CQL/ECQL parsing with regard to date/dateime parsing.

- modified grammer adding TEQUALS operator
- modified grammer to allow for date literals in regular binary comparison (ECQL)
- fixed some issues with regard to timezone offset handling
- made date/time/timezone extraction more robust with regular expressions
Merge pull request #147 from jdeolive/cql_date

Improvments to CQL/ECQL parsing with regard to date/dateime parsing.