* replaced old status with 2 flags for unread and starred
* add fields to db, replace int(1,0) with booleans in sql queries, removed StatusFlags class + refactor code relying to it
* add repair step for migration
* again use integer(1,0) instead of bool in sql queries, because of sqlite doesn't support true/false
* add/fix unit tests for new boolean status
* set unread/starred flags as statements in sql
* fixed mysql unknown column items.unread, fixed marking of read items on repair step
* remove unnecessary bool casts
* add empty checks to Items::is* methods
* update migration to use native sql instead of the querybuilder
* don't cast the flags manually, let the api do the work
