blend2gltf: fix conversion error if is in Pose or Edit mode

[rdb]

Adds tests for both these cases. Tested with Blender 2.79 and 2.80.

Fixes #18

[Moguri]

Thanks for the fix and also supplying tests! However, the test is failing the lint checks:

C: 15, 0: Wrong continued indentation (add 4 spaces).

        [os.path.join(SRCDIR, 'edit_mode.blend')],

        ^   | (bad-continuation)

C: 16, 0: Wrong continued indentation (add 4 spaces).

        os.path.join(tmpdir, 'edit_mode.bam'),

        ^   | (bad-continuation)

C: 17, 0: Wrong continued indentation.

    )

    ^      || (bad-continuation)

C: 22, 0: Wrong continued indentation (add 4 spaces).

        [os.path.join(SRCDIR, 'pose_mode.blend')],

        ^   | (bad-continuation)

C: 23, 0: Wrong continued indentation (add 4 spaces).

        os.path.join(tmpdir, 'pose_mode.bam'),

        ^   | (bad-continuation)

C: 24, 0: Wrong continued indentation.

    )

    ^      || (bad-continuation)

C:  6, 0: Constant name "use_gltf28" doesn't conform to '(([A-Z_][A-Z0-9_]*)|(__.*__))$' pattern (invalid-name)

C:  7, 0: Constant name "settings" doesn't conform to '(([A-Z_][A-Z0-9_]*)|(__.*__))$' pattern (invalid-name)

C:  4, 0: standard import "import os.path" should be placed before "from blend2bam import blenderutils" (wrong-import-order)

Could you please fix these up? I can also clean them up before merging, but it might be a while before I get around to it.

[rdb]

@Moguri Done.

[Moguri]

Thanks!