Blender Git Loki

Fix modal bevel OP immediately stopping when called using enter key from search menu

Steps to reproduce were:
* Go to edit mode, select geometry
* Spacebar -> search for bevel OP
* Activate *using enter key*
* Immediately stops when releasing enter key

To fix we simply make sure the initial release event is ignored. For mouse events that wasn't an issue since activating an element is done on key release in menus. An alternative fix would be to do the same for enter key, but that's more risky. Also, checking event value is highly recommended anyway.