Blender Git Loki

Cleanup: remove editor from static function names

Move e_data to IMAGE_PrivateData

Renamed draw/engines/editors to draw/engines/image

Initial commit for image unavailable texture

Silenced warning in draw_view.c

UV Line drawing: better screen space perp

Fix: UV Dash drawing

Merge branch 'master' into uvimage-editor-drawing

Use premultiplied alpha

Merge branch 'master' into uvimage-editor-drawing

Merge branch 'master' into uvimage-editor-drawing

Use DrawManager for Image/UV Editor

This project moves the current UV/Image editor drawing to the draw manager. Why would we do this:
**Performance**:
- current implementation would draw each texel per time. Multiple texels could be drawn per pixel what would overwrite the previous result. You can notice this when working with large textures.
- repeat image drawing made this visible by drawing for a small period of time and stop drawing the rest.

**Alpha drawing**:
Current implementation would draw directly in display space. Giving incorrect results when displaying alpha transparent images.
Old:
{F8780114}

New:
{F8780113}

This addresses {T52680}

**Current Limitations**
- The project can be activated in the user preferences as experimental features. When support of huge textures is implemented we can switch over.
- Using images that are larger than supported by your GPU are resized (larger than 16000x16000). This leaves some blurring artifacts. We want to solve this after this patch has been reviewed and committed. Users will notice that the image is blurred a bit when zoomed in and looking at actual pixels.

**TODO**
* [ ] drawing of image unavailable grid. Need to check the use case for the current grid thing.
* [x] drawing of masking + render info etc.
* [ ] painting does not update the GPU textures.

**Future**
* Use smaller GPU textures when zoomed in.
* Support huge texture sizes.
* Migrate mask drawing to draw manager.

Maniphest Tasks: T67530

Differential Revision: https://developer.blender.org/D8234