Fix cc2530 DMA priority define values

Fixes #156
Merge pull request #157 from g-oikonomou/issue-156

Fix cc2530 DMA priority define values
Added support for <input type='hidden'>.

Hidden form fields are aded to the page attribute buffer like text form fields so there's no need for special treatment in formsubmit(). However they are not added as widgets to the window so there's no user interaction.
Merge pull request #159 from oliverschmidt/master

Added support for <input type='hidden'>.