BlinkenWall added drawPoint to draw a single point

 * Add drawPoint(x,y,z,color) to BlinkenWall
 * rewrite drawAnimation to share code with drawPoint
 * add default background color to constructor
 * draw default Background color on clear()
 * update example in REAMDE
Fix draw_raw() compile error

 * use color instead of colval
 * add setBackGround(unit32_t) to change the default background
   color.
remove old example which came with last commit

 * remove gameover.ino
Merge pull request #3 from sahne/master

BlinkenWall library version 0.2