unit name and colors changed to pointers
change par->lty to a pointer
remove field length constants
change viewport name to pointer
set line width using angle
Remove viewport angles for now
flip the y axis in grid_apply_viewport_transform
factor out applying line parameters
add grid_rect funciton
change the argument order to grid_line for better consistency
implement grid_text and get first example to compile
get rid of the new_grid_par constructor
Add some colors for convenience