A lot changes on jcore:

A lot changes on jcore:
- Implemented doSelectByCriteria() in MySQL backend
- Close only connection in same backend if it is still open
- Added method size() to Result/DatabaseResult
- Moved member entrySet() in BaseCriteria to proper location
- Fixed comments of interface Criteria and SearchableCriteria
- Some trace/debug messages added
- Now database frontends have a new method getResultFromSet() which transforms a ResultSet (SQL) to a Result (jcore)
- Sorted class/interface imports
Signed-off-by:Roland Häder <roland@mxchange.org>