Resolved cyclic calls for editors.
Now there's a space_api/ module, here you can use functions calling
other editor modules. The functions in the module are only used by
the WindowManager module to initialize space types.
Note for sconzers and MSVC and cmake: the proper linking order for
editors is:
- space_api
- space_xxx
- object / mesh / transform / etc
- interface
- util / datafiles
- screen
