Scilab keyword

alufunctions - pixel drawing functions

### Description

src is the source ie the "value of the pixel" which we want to draw. dst is the destination ie "value of the pixel" which is already drawn.

  - 0 : clear ie "0"
  - 1 : and ie "src AND dst"
  - 2 : and reverse ie "src AND NOT dst"
  - 3 : copy ie "src"
  - 4 : and inverted ie "(NOT src) AND dst"
  - 5 : noop ie "dst"
  - 6 : xor ie "src XOR dst"
  - 7 : or ie "src OR dst"
  - 8 : nor ie "(NOT src) AND (NOT dst)"
  - 9 : equiv ie "(NOT src) XOR dst"
  - 10 : invert ie "NOT dst"
  - 11 : or reverse ie "src OR (NOT dst)"
  - 12 : copy inverted ie "NOT src"
  - 13 : or inverted ie "(NOT src) OR dst"
  - 14 : nand ie "(NOT src) OR (NOT dst)"
  - 15 : set ie "1"