Merge branch 'blender2.8' into topbar

Merge branch 'blender2.8' into topbar

Keeping the branch for now, I might delete it soon though.

Fix unintentional changes from merge conflicts

Merge branch 'blender2.8' into topbar

Move data of global areas into a separate struct

Made the struct accessible via a pointer in the ScrArea so that we can
use a simple NULL-check for this pointer to see if the area is global.

The struct is not written to files, meaning we have the freedom to do
changes to it without having to worry about compatibility.

Support hiding the lower sub-bar by dragging the area edge up

Fix hint for makesdna to not write top-bar struct commented out

Just did this for testing, but should not have ended up in the commit.

Bring back unintentionally removed error print

Topbar: disable redo properties in topbar entirely for now, behind #ifdef.

This is going to be different with the tool / command separation plans, so
let's not confuse users for now.

Fix error from one of the merges, this line should have been removed.

Tweaks to topbar versioning code

* Don't write global area pointers at all, leaves .blends a little
cleaner without broken pointers.
* Don't call editors functions from blenloader.
* Fix black topbar when loading some existing 2.8 saved .blends.

Merge branch 'blender2.8' into topbar

Fix typo in #define

Make global areas use properly managed screen-verts and screen-edges

* Added functions for ScrAreaMap to avoid code duplication
* Fixed loading files without top-bar not adding top-bar at all

Add ScrAreaMap struct wrapping screen-areas, -edges and -vertices

Global areas will need to use the edge and vertex lists in future too.
Once the topbar branch is merged, we can also change bScreen to use this
struct, avoiding code duplication.

Don't allow changing area into topbar editor, hide its menu item

We probably want to allow Python scripts to check if an area is the
topbar or later the status bar. Not sure if that'll work right now, I
can't test since global areas are not iterable through BPY at all.
Maybe that's fine too ;)

Disable toolshelf redo regions for now

Inteded to do that in rB223f4fa583cb386 already, but forgot to comment
out again after testing...

Don't write topbar data into files (yet)

We decided to do this so we don't have to care much about compatibility. The
code for writing is just #ifdef'ed out so it can easily be brought back.

Bring back toolshelf redo region, ifdef'ed out though

Just for until the design is better defined. Also moved SpaceTopBar
struct to a better place in its DNA file.

Only remove info editors on top of the window using the full width

Removing all info editors could cause issues. Wanted to get proper
layout resolving to work, but wasted more than an entire day on that.
Still planning to look into that again though.