Fix ply import tests.

The function for clearing out objects in the startup file
needed updating for 2.8 collections api.

Fix export_obj_cube test.

Verified that current export files for all_quads.blend are good,
then updated expected MD5 hash to match current files.

Fix T63071: Bevel inconsistent results toggling harden_normals.

Some iterations in bevel were over a hash table, which leads
to possibly different results run-to-run, especially when
loop_slide is enabled. Changed those iters to go over all verts
of BMesh, which leads to consistent order run-to-run.

Fix bl_pyapi_idprop unit test.

Scenes can now have a 'cycles' key when starting, so account for that.

Bevel: revert idea of always starting in offset mode.

Commit 208fafb to fix bevel tool units included a change to always
start modal in offset mode. This was may or may not be right but
broke a way in which users could set percent mode and then subsequently
start a modal that bevels in that mode. So going back to old way.

Fix T61773 Bevel and Inset mouse sensitivity, and bevel tool units.

The mouse movement scale needed adjusting according to object scale,
since the amount is on the unscaled model but the viewport shows the
scaled one.
Also fixed proper units for amounts in bevel tool, as was already
done for modifier. Percent should be comfortably adjustable by mouse.

Fix T61988, Bevel miter on small scale.

Take two at fix, hopefully without unintended commits
to submodules this time.

Revert "Fix T61988: Bevel mitering on small objects."

This reverts commit 048088e1d2435d249f36feb4774d14aeaf1293e9.
Accidentally changed submodules. Will resubmit with only
intended changes later.

Fix T61988: Bevel mitering on small objects.

When edges had small length (less than about .005) the angle
classification didn't work. Needed some normalization of vectors.

Bevel mod: cleanup flags and extra data.

Removed a clnors field unneeded after a recent refactor.
Finished deprecation of flags that haven't been used since pre-bmesh.