Crunch ROM icon sprites
Jeffrey Lee authored
Save around 50KB of ROM space by converting the icon sprites to use RISC
OS 3.5 mode words instead of numbered modes, reducing the size of the
mask data to around a quarter of its old value.

Tested in IOMD ROM, with boot sequence disabled (to ensure the ROM
sprites get used).

Version 5.82. Tagged as 'Wimp-5_82'
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