improved style of crud_display_table buttons
moved save/cancel butons on edit and delete dashboard views down to a grey footer at the bottom of their windows (to be more consistent with the rest of c5 dashboard styles)
made the body-type filter on the cars dashboard page more generically named so it does not need to be changed when using the boilerplate for new projects
more robust check for existence of many-to-many record in the cars dashboard edit page (colors checkbox)
segment_id is now optional on the add method of the primary record (so you can add a new car without having chosen a body_type_id first)
in car model delete method, moved parent::delete call to end of function so associated records get deleted from the db before the primary record
crud_display_table no longer outputs a table head if no columns have labels; narrowed the width of some dashboard pages
explicitly cast ids to integers when passing them to ADODB as query vals (otherwise it treats them as strings which causes sub-optimal queries)
added URL Slug example (including auto-fill functionality, just like C5 add-new-page dialog)