[Examples] Remove old code

[discoleo]

Examples: Old code

• there is some old code, which uses the wrong function names;
• this code must be removed;

Old code

### Ex 1:
plot.base()
x = c(0,10); y = c(1, 5);
arrowDH(x, y, lwd=2);

### Ex 2:
x = c(0, 6); y = c(1, 6);
arrowInvH(x, y, lwd=2);

### Ex 3:
arrowDH(x, y*2 - 2, d = 0.3, lwd=2, col="blue");

[discoleo]

See sent code!

[DarianFlorianVoda]

Removed.