GP: Change Thickness Profile panel

Merge branch 'blender2.8' into greasepencil-object

GP: Fix problems with stroke Caps

Now the start cap is done and during drawing the end cap is not set because needs to have a UV calculated and this is not done while drawing.

GP: Set Brush default material when add new GP Object

Before the brush color was not set equal to object active color.

GP: Remove Object Onion Skin switch

It was confusing to have two switches.

GP: Replace Clamp icon

GP: Make Onion Skin ON as default RNA value

GP: Enable Object Onion Skin by default

Now, the main switchis on, and the layer onion skin is off.

GP: Use a fixed UV data for buffer end cap

GP: Fix problems with stroke Caps

Now the start cap is done and during drawing the end cap is not set because needs to have a UV calculated and this is not done while drawing.

Merge branch 'blender2.8' into greasepencil-object

Conflicts:
source/blender/blenloader/intern/versioning_280.c

Edit Mesh: Fix edges poking through the verts points in xray/seethrough mode

DRW: Batch Cache: Add batch request system

This makes it possible for engines to ask for batches and only fill their
data after all engine populate functions have run.
This means that, when creating the batches data we already know all the
batches that are needed for this redraw and the needed data.

This allows for less redundant data preparation and better attrib masking.
Ideally, we should run all viewports populate function before executing
the batch construction but this is not the scope of this patch.

Conversion from the old request method will be progressive and both can
coexist (see uses of mesh_create_pos_and_nor()).

GPU: Make changes to GPUIndexBuf and GPUVertBuf to allow multithreading

This is a small change. We delay all gl calls at the first use of the
GPUIndexBuf / GPUVertBuf in order to be able to create multiple buffers
from different threads without having many gl contexts.

Edit Mesh: Draw inner edge selected in vert edit mode if both verts selected

This only make the edge fully selected. There is still no gradient like in
2.79 when only one vertex is selected.

Edit Mesh: Make "fresnel effect" not transparent but mix between 2 colors

Alpha blending is causing too many issues.
Revert back to something simpler.

Edit Mesh: Opti: Reduce max_vertices in geometry shader

This is a really small win that had been overlooked when optimizing the
shader.

GPU: Cleanup: Rename vbo to ibo for index buffers

DRW: Batch Cache: Mesh: Port more batches to batch request method

DRW: Batch Cache: Mesh: Port edit mesh batches to batch request method

This also do some renaming/cleanups.