Blender Git Loki

Cleanup: style guide, reorder classes, comments

https://wiki.blender.org/wiki/Style_Guide

Changes here:
Move non trivial and non-inlined implementations to cc files instead
of header files.

Reorder classes according to style guide.

Remove documentation comments from header files and keep it near
implementation

Break up some functions into smaller ones: `insert_frame_in_path` etc.

Use reference as much as possible, instead of pointers.

Move `_` prefix to suffix of private class members.

Clean up warnings of implicit float conversions, uint conversions.

Use `ATTR_FALLTHROUGH` in switch cases. Move break inside the case
braces.

Remove `blender::io::obj::OBJ_export` function. It was a mistake.

Use `const` in getters.

Fix T78533: Skip image texture if image filepath is empty

Export smooth groups for smooth shaded meshes.

Fix GPL license copyright year

Remove object filtering code from export_frame.

Also return early if the file cannot be opened before looping over all
the objects in a frame.

Use BKE_mesh_calc_poly_normal

Replace custom normal calculation function with an existing function.

Add null check for dvert

Rename get_object_deform_vert; add comments

`get_object_deform_vert` ? `get_poly_deform_group_name`

Edit comments, and the UI tooltip of the export option.

Merge branch 'master' into soc-2020-io-performance

Fix same group name being duplicated.

Prefix `r_` to values being modified in other functions.

Reorder arguments in vertex group and material functions for
consistency.

Resize deform group only upto total groups present.

Support vertex group to which a face element belongs.

Differential Revision: https://developer.blender.org/D8170

Replace nodes_with_idname with nodes_by_type

The former was removed in
{84901f2edaf1}

Merge branch 'master' into soc-2020-io-performance

Cleanup: simplified conditionals, remove warnings on linux

Use unsigned int to avoid any range issues.
Remove trailing whitespaces in face elements.
Remove `== false` from conditionals.

Use unique_ptr to avoid early destruction of new meshes.

Cleanup: AT was redundant in the destructor debug

Remove redundant call to OBJMesh destructor.

Fix build issues: namespace BKE > bke

{b51d6e8012e5}

Merge branch 'master' into soc-2020-io-performance