Merge pull request #50 from mikey179/master

features for 2.4.1, fixes #49
raise dependencies
  * the following methods now except anything that can be casted to an instance of `net\stubbles\lang\types\Date` via `net\stubbles\lang\types\Date::castFrom()`
     * `net\stubbles\input\ValueReader::asDate()`
     * `net\stubbles\input\filter\range\DateRange::__construct()`
     * `net\stubbles\input\filter\range\DatespanRange::__construct()`