[GRASS5] new symbols

[Hamish]

> I have just made a new star icon

In 6.1-cvs I have now updated the star symbol to be the 5-point star.
The old 4-point star is now called extra/4pt_star.

basic/ was getting cluttered so I moved airport, compass, and target
symbols into extra/ which I think is a more appropriate place for them.

Also just added the extra/half-circle symbol. This can be used on top of
the basic/circle symbol to create any (left|right) side of circle color
combinations. (left side color is half-circle fill-color, right side
color is full circle fill-color)

A basic/triangle symbol was added to 6.1-cvs some time ago.



Hamish