Add the argument verify code to setCurrent() and setCurrentNotify() method
Add the argument verify code to setRange() methods
In NumberPicker constructor, if the range end is less than the start position, swap them for safe
Fix negative value handling
Preserve cursor position when updating the EditText view
Replace resource id name: 'timepicker' -> 'numpicker'
Call recycle() for used TypedArray object
Merge pull request #14 from roubert/dev

More house keeping: Fix a lot of different details.
Merge pull request #16 from h6ah4i/fix_negative_value_handling_and_small_bugs

Fix negative value handling and small bugs