board takes array as prefilter, fix data test
add board options and settings for including None in rows and cols
use board options to include None in rows and cells
add option to include closed elements (for taskboard)
Revert "css 2.1 does not define position for table elements. An additional div fixes addbutton on firefos"

This reverts commit 20446726d6db69478c8bfe1b40dd6cfdf992b70f.
save option for closed elements
fix firefox add button again
fix cancelling add element