Only consider visible fields

See https://github.com/hananils/parenthesistabs/commit/d3cf040936c89763c24073dd48dc566656a588ec
Improve text node selection

See https://github.com/hananils/parenthesistabs/commit/4a4decb07a51b2643387d77b4bf1ac4c3f32506a
Copy and paste stupidness
Add keyboard navigation via tabs based on @jensscherbl's work. Make sure that complex fields with multiple inputs are considered.

See https://github.com/hananils/parenthesistabs/commit/ecca887dde9dc86401f82bcf0d5ae6de0d31ed93
Merge branch 'master' of github.com:hananils/parenthesistabs
Version 0.2