Non-human HUD polishing (stop pulling and intent buttons)

Added a _"stop pulling"_ button to monkey and alien larva HUD and make the _"intent button"_ use the current HUD theme.

Partially fix #3577 (doing so for simple mobs and slimes would involve doing a HUD from scratch for them).

__Monkey (midnight ui used) :__ 
![monkey_pullin](https://cloud.githubusercontent.com/assets/7117411/3105609/c4009a42-e674-11e3-96f9-11c1f1908282.png)

__Larva :__
![larva_hud](https://cloud.githubusercontent.com/assets/7117411/3105611/c692bf06-e674-11e3-9819-76ab861b5928.png)

__Alien (intent button) :__
![alien_hud](https://cloud.githubusercontent.com/assets/7117411/3105610/c5982992-e674-11e3-8364-45afd903ba08.png)