remove support for 'ajax_submit'
Merge pull request #25 from scribu/no-more-ajax

remove support for 'ajax_submit'
avoid variable variables in scbBoxesPage::boxes_init()
add toplevel menu as a submenu too
cast choices and selected values to strings before comparing

this is better than using === because it correctly handles edge cases where
either choices or values are cast to numbers

fixes #26
introduce scb_list_group_by()
add optional 'table_options' parameter to scb_install_table(). see #27
bump revision to 59
run form_handler() in page_loaded()

this allows doing redirects after form handling