Show a "pointer"-type cursor for clickable form elements.

This commit changes the default cursor type to "pointer" for
the elements "label", radio buttons, checkbox and select to hint
that they are clickable elements.
Merge pull request #42 from dcruz/develop

Show a "pointer"-type cursor for clickable form elements.
Thanks @dcruz
Merge branch 'develop' of https://github.com/sapo/Ink into develop