multiple cassettes are available it is clear which drive controls are
displayed (see e.g. sol20 or pet2001 with "-tape2 c2n" slot). also
cleaned up some function names and better described the usage of
the devctrl.h base class. nw.
as follows:
MAKE_RGB(r,g,b) == rgb_t(r,g,b)
MAKE_ARGB(a,r,g,b) == rgb_t(a,r,g,b)
RGB_ALPHA(data) == data.a()
RGB_RED(data) == data.r()
RGB_GREEN(data) == data.g()
RGB_BLUE(data) == data.b()
RGB_BLACK == rgb_t::black
RGB_WHITE == rgb_t::white
Implicit conversions to/from UINT32 are built in as well as simple
addition, subtraction, and scaling (with clamping).
As a result of being a class, some stricter typing was needed in
a few places but overall not too much.
