Fixed : CPDatePicker textual issues

This PR fixes several issues about the textual CPDatePicker :
- Fixed the issue about keyView loop when not assigning the nextKeyView
- Changed the behavior of the component when editing or deleting the date. It works as in cocoa now.
- Fixed bug about frameSize of each component when editing
- Fixed bug about NaN or null values
- Added optimization
- Refactoring the code