Minor changes to remove checks for logically impossible situations

[TheRealMothebad]

Two changes:

1. The tool_event InputEvent is either a MouseMotion or a MouseButton, so the check for the InputEvent being a MouseButton event does not need to occur if the object is already identified as a MouseMotion.
2. In the tool_event MouseButton path, if the elif section is reached then event.pressed is guaranteed to be false, so checking that it is false is redundant.

[mbrlabs]

Thanks!