Merge pull request #85 from mikey179/master

add net\stubbles\lang\types\Date::castFrom()
net\stubbles\lang\types\Date::isBefore() and net\stubbles\lang\types\Date::isAfter() now except anything that can be casted via net\stubbles\lang\types\Date::castFrom()
use next minor version instead of bugfix version
  * added several shortcut methods on `net\stubbles\lang\types\datespan\Datespan`:
     * `startsBefore($date)`
     * `startsAfter($date)`
     * `endsBefore($date)`
     * `endsAfter($date)`
     * `formatStart($format, TimeZone $timeZone = null)`
     * `formatEnd($format, TimeZone $timeZone = null)`
increase support for date casting