005 - minor bug fixes and button disables!

- fixed slight bug where it wouldnt update the stat window if cash
zombies hit him
- fixed bug where vision could still be bought at the store, even though
there is no FOV
- can now "disable" buttons - disabling clicks and darkening the buttons
image
...added changeBrightness(img,factor) to gameFunctions and also added a
few related constants
- fixed a bug where nearby cash zombies would freeze if one was touching
me
...the line returnWin = WIN_STAT fixed it, instead of instantly
returning the window