implement context menu, still in progress
implemented action mode for edit categories activity
implemented correct highlighting for selected items
implemented keyboard appearing for edit category dialog
implemented removing of category
handled null values in category
implemented "delete" handler for action mode in main fragment
delete dialog changed from AlertDialog to DialogFragment
implemented view pager tabs
implemented actionmode and actionbar for changemonth activity
begin bugfix for categories
fixed bug with incorrect default category handling
new icons added to git
fixed bug with incorrect default category handling