Redraw of dragboxes when being resized/translated optimised to reduce flicker.
Ben Avison authored
Autoscroll update period extended to 12cs to reduce flicker.

Added Wimp_ReadSysInfo 17 to return configured drag-and-drop scroll startup
delay (in cs) because the CMOS storage isn't easy to read.

Identified and bracketed changes from 3.9x responsible for 24-bit icon colours.

defaultfontcolours now works correctly again.

Introduced new icon colour code. This holds icon colours in 24 bits internally
throughout, rather than treating 24-bit colour specifiers as a special case.
This results in the following bugfixes/improvements:
 * 3D faces and moat colours, and slabbed-in action button backgrounds, can
   all be specified in 24-bits
 * fading of icons is now consistent across icon types, and utilises the
   colour range of >16 colour modes
 * 3D borders now get faded along with the rest of the icon
 * action buttons can now contain sprites (background is correct, and sprite
   is not inverted)
 * various cases where anti-aliasing didn't blend in to the background
   correctly are now fixed
 * conventional and 24-bit specifiers now behave equivalently to each other -
   the same colour specified either way behaves the same when faded, used as
   an EOR colour etc. (greys are now always dithered in 1-bpp modes, even if
   specified in 24-bit)
 * behaviour is now the same whether the Wimp font is the system font or a
   fancy font (amazingly, this wasn't always the case)
 * except for 3D icons, if the icon background matches the work area
   background, it is unaffected by fading - so for example, group boxes can now
   be faded correctly

Switched out AutoHourglass (Mike was concerned about the speed hit).

Corrected *Help syntax strings for On/Off configuration options.
cb05448e