Apache Forrest code update

code update
by
NKB
:

Automatic generation of borders from skin colors and naming convention.
Rounded and straight 45 degrees corners supplied.

For example, to generate a 'r'ounded corner for 't'op 'l'eft the size
of '5' pixels of background 'header', foreground 'tab-selected' and
border of 'tab-unselected' I can just ask for:

/skin/images/rc-t-l-5-1header-2tab-selected-3-tab-unselected.png