Fix building with and without WITH_LINEART

Merge branch 'lanpr-under-gp' into temp-lineart-contained

Merge remote-tracking branch 'origin/master' into lanpr-under-gp

Merge branch 'lanpr-under-gp' into temp-lineart-contained

LineArt: Proper Use of BMesh operator to remove doubles.

LineArt: Complete UI in the modifier.

Merge remote-tracking branch 'origin/lanpr-under-gp' into temp-lineart-contained

# Conflicts:
# extern/ceres/README.blender
# release/scripts/startup/bl_ui/space_userpref.py
# source/blender/blenkernel/BKE_gpencil_curve.h
# source/blender/blenkernel/BKE_gpencil_geom.h
# source/blender/blenkernel/BKE_layer.h
# source/blender/blenkernel/BKE_screen.h
# source/blender/blenkernel/intern/gpencil_curve.c
# source/blender/blenkernel/intern/layer_utils.c
# source/blender/blenloader/intern/versioning_290.c
# source/blender/draw/engines/overlay/shaders/edit_curve_point_vert.glsl
# source/blender/draw/engines/overlay/shaders/wireframe_vert.glsl
# source/blender/editors/gpencil/annotate_paint.c
# source/blender/editors/gpencil/gpencil_convert.c
# source/blender/editors/gpencil/gpencil_edit.c
# source/blender/editors/gpencil/gpencil_intern.h
# source/blender/editors/gpencil/gpencil_interpolate.c
# source/blender/editors/gpencil/gpencil_merge.c
# source/blender/editors/gpencil/gpencil_mesh.c
# source/blender/editors/gpencil/gpencil_paint.c
# source/blender/editors/gpencil/gpencil_select.c
# source/blender/editors/gpencil/gpencil_trace_ops.c
# source/blender/editors/gpencil/gpencil_utils.c
# source/blender/editors/interface/interface_panel.c
# source/blender/editors/physics/physics_pointcache.c
# source/blender/editors/space_buttons/buttons_context.c
# source/blender/editors/space_outliner/space_outliner.c
# source/blender/editors/space_view3d/view3d_placement.c
# source/blender/makesdna/DNA_userdef_types.h
# source/blender/makesrna/intern/rna_scene.c
# source/blender/makesrna/intern/rna_space.c
# source/blender/python/gpu/gpu_py_shader.c

LineArt: Merge changes

Merge remote-tracking branch 'origin/master' into lanpr-under-gp

# Conflicts:
# release/datafiles/locale
# release/scripts/addons
# release/scripts/addons_contrib
# source/blender/blenloader/intern/versioning_290.c
# source/blender/makesdna/DNA_brush_types.h
# source/blender/makesdna/DNA_gpencil_modifier_types.h
# source/blender/makesrna/intern/rna_scene.c
# source/tools

LineArt: Ris for New APIs

LibOverride: Do not tag overrides for complete recalc.

This was done as some sort of safety, but should not actually be needed,
and including tags like `ID_RECALC_POINT_CACHE` e.g. makes usage of
point caches impossible with liboverrides (since it would systematically
invalidate all cache on file load).

In theory we should not have to tag anything here in fact, RNA accessors
are supposed to take care of it, but for now we keep the
`ID_RECALC_COPY_ON_WRITE` one.

Part of first step of T82503: support disk cache in liboverrides.

GPencil: Cleanup clang format

Collections: Prevent setting scene collection color tag from rna

It should not be possible to set the scene collection's color tag
through rna. Also adds a missing notifier for setting the collection
color tag from python.

LibOverride: Make PointCache RNA properties overridable.

Note that due to convoluted layout of point caches in RNA (active one
also storing list of all available ones), we'll often have the
pointcache overrides rules twice. Should not be a huge problem,
practically speaking.

Part of first step of T82503: support disk cache in liboverrides.

UI: Remove remaining uses of old collection icon

After rB452a1c7b3838 there were still a few cases where the old
collection icon was used in the interface. Replace these with the new
filled collection icon.

Outliner: Fix memory errors in runtime data

Fix a heap-use-after-free when duplicating outliner editors, and fully
free runtime data when freeing outliner editors.

Cleanup: Make panel type flag names more clear

The overlap with the `Panel` flags that start with "PNL" was quite
confusing because wasn't clear which enum a flag was from. The
new names are a bit longer, but the clarity is worth it.

GPencil: Remove "angle_split" from Multiply modifier.

GPencil: Missing initialization in previous commit

Ceres: Update to upstream version 2.0.0

We already were using one of earlier RC of the library, so there is no
expected big changes. Just making the update official, using official
version and stating it in the readme file.