Blender Git Loki

Cleanup: remove unused brushes

Brush: split out vertex paint tool & blend mode

- Vertex & weight paint now use the 'blend' setting.
- Weight paint now has it's own tool setting,
since weight paint doesn't deal with color - we'll likely
support different tools eventually.

Cleanup: rename fast-heap -> heap-simple

In general prefer API names don't start with adjectives
since it causes grouping of unrelated API's for completion.

Cleanup: move fast heap into own source & header

Tool System: use tool type enum to access brushes

Previously the brush names were used which had the limit that:

- Brush names that were deleted wouldn't show up in the toolbar.
- Naming collisions between user defined brushes and existing tools
broke tool selection.

Now brushes are created as needed when tools are selected.

Note, vertex/weight paint combine tool and blend modes,
this should be split out into a separate enum.

Cleanup: style

Fix/Updated Object API example.

Was still 2.7x code... ;)

Fix (unreported) potential race condition in view_layer_bases_hash_create().

When you check for undone work before acquiring a lock that ensures you
are the only one actually doing the work, you have to redo the check
*after* acquiring said lock.

Otherwise, there is room for nasty random race condition issues...

GP: Limit internally Time offset to something logic

If the offset is greater than frame range, the offset could gets some unlogic values, so now the value is normalized in the range.

API Docs: gpu api introduction + examples

GP: More tweaks to Time Offset

BLI_heap: implement a limited but faster version of heap.

If the user only needs insertion and removal from top, there is
no need to allocate and manage separate HeapNode objects: the
data can be stored directly in the main tree array.

This measured a 24% FPS increase on a ~50% heap-heavy workload.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D3898

GP: Fix Time Offset bug when use range

The frames greater than frame range were wrongly calculated.

Wireframe: Extend Xray slider range

This makes it possible to bypass the depth dithering effect at the cost
of less accurate depth perception.

Eevee: Fix "Show Irradiance/cubemap" icons

UI: Make the grid alpha themable

Now that the 3d grid is infinite, antialiased, not occluded, and overlaid
on top of rendered view, being able to decrease its opacity to reduce
visual strain is a must.

DRW: Fix crash with deferred compilation

Edit Mesh: Fix wire opacity when not rotating the view in Xray mode

LightProbe: Fix description of influence type

GP: Change Lock icon and Popover title