Define what the term 'screen' means in the context of the specification.
Increase clarity when lockOrientation() locks to current orientation.
Merge pull request #19 from mounirlamouri/lock_no_change

Increase clarity when lockOrientation() locks to current orientation.
Merge pull request #16 from mounirlamouri/screen_definition

Define what the term 'screen' means in the context of the specification.
Remove the ability to lock to angles.
Add 'natural' orientation lock type.