added subtype admin without onchange javascript
improved redirect js-function and moved function to seperate file
removed _ before event id in urls
fixed cat filter on front page

issue #18
initialize static variables Last_event_startdate and last_event_enddate

issue #50
renamed "ytd" to "actual_date" and added "all" option to initial_date to show all dates
added shortcode attribute "initial_cat"
renamed date_range to date_filter
added shortcode attribute "date_filter" (not implemented yet)
fixed date and cat filter in admin event table
fixed dropdown when the event details are displayed
added shortcode attribute "filterbar_items" (not implemented yet)

issue #18
implemented shortcode attribute filterbar_items (not completed)

issue #18
implemented options for filterbar-items

issue #18
change filterbar-item-option seperator from comma to pipe for easier validation
implemented show_past option for years filter

issue #18
implemented reset filterbar item

issue #18
renamed url parameter "ytd" to "date"
fixed some css issues

issue #48
filter elements acc. date_ and cat_filter in filterbar