Input: Update mouse position on mouse-button events.
Input: Update mouse position on mouse-button events.

(cherry picked from commit 468719c480100a0d5c8e5c5760f7f38f6a857d4a)

pixelpicosean/my-godot-2.1,pixelpicosean/my-godot-2.1,pixelpicosean/my-godot-2.1,pixelpicosean/my-godot-2.1,pixelpicosean/my-godot-2.1