Blender Git Loki

Tool System: adjust Smooth/Randomize modal operator behavior

Previously the default values were left non-zero to avoid having to
update scripts. However, this meant it wasn't possible to setup
non-modal key bindings for smooth & randomize.

Now these operators follow logic of many other operators where setting
the value executes immediately, leaving unset runs modal.

Existing keymaps & scripts will need to be updated.

Addresses issue raised in f4a4ec84255a.