Make document model static and add some document related methods

Change-Id: Ibcb863e67a2433529c9d2b6dec237f9d8b1d8d50
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Work with documents instead of editors where possible in debugger

And where using editors is necessary, take *all* editors into account,
not a random set of what previously was called "original" editors (when
using splits).

Change-Id: Id6bbad08f3083b6744fc2edcf0b87ba504d3257b
Reviewed-by: hjk <hjk121@nokiamail.com>
Don't use openedEditors in CMakeProject

Work on documents instead.

Change-Id: I7000d10b2a885d5dc22c9b40377c9521f21b6195
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>