Added an "Exponent" slider to Color Boundary brush.

Tweaked value for smoothing in vcol boundary tool (a slight amount of
smoothing is applied to prevent normal discontiuties from perfectly
colinear triangles).

Also reverted some CLANG compiling stuff.

Cleanup: Remove unused variable

Refactor: move Object .blend I/O to IDTypeInfo callbacks

Refactor: move Screen .blend data read to blenkernel

Ref T76372.

Cleanup: fix naming and remove unnecessary code

View3D: take clipping into account for Frame All

Clamp the min/max used for Frame All/Selected
by the clipping region if it's set.

Resolve T81050

Cleanup: move plane array intersection into a function

Also add check to ensure a point isn't occluded by it's own plane,
which could happen if a small epsilon values are passed in.

Cleanup: remove unused includes in readfile.c and writefile.c

Cleanup: Rename render texture files to texture_*

Refactor: move Ipo .blend I/O to IDTypeInfo callbacks

Fix missing include warning

Caused by rB580ff2cb937daf43699908afe1190baea8d117aa

Cleanup: Clang-Tidy modernize-use-nullptr

Replace `NULL` with `nullptr` in C++ code.

No functional changes.

Clang-Tidy: error out when executable not found

Stop with an error when the Clang-Tidy executable cannot be found.

Without this check, CMake will happily report "Found Clang-Tidy" but with
the fallback version (0, 0, 0), when `CLANG_TIDY_EXECUTABLE` points to a
non-existing executable.

Refactor: move Pose .blend I/O to blenkernel

Ref T76372.

Refactor: move MotionPath .blend I/O to blenkernel

Ref T76372.

Fix T81997: Subsurf Optimal Display sticks after object conversion

When using Optimal Display, some edges are not flagged `ME_EDGEDRAW` |
`ME_EDGERENDER`.
When the modifier is applied through the UI in the modifier stack this is
not an issue because the `modifyMesh` callback is run with
`MOD_APPLY_TO_BASE_MESH` (this will effectively turn of Optimal
Display).
When converting to mesh though, this will just get an evaluated mesh
(where the edge flags are still the same as with the subdivision
modifier).
Now ensure every edge is flagged to draw after conversion.

Maniphest Tasks: T81997

Differential Revision: https://developer.blender.org/D9331

Cleanup: Clang-Tidy, modernize-make-unique

UI: Improved macOS Application Icon Progress Bar

Nicer appearance for the progress bar that is drawn over the application icon during long processes on macOS.

Differential Revision: https://developer.blender.org/D9398

Reviewed by Brecht Van Lommel

Refactor: move gpencil modifier .blend I/O to blenkernel

Ref T76372.