Remove unneeded components
Add ImageLibJPEG to Disc to prevent ImageLib failing the export libs phase with an error, ideally ImageLib needs fixing so it isn't split in this fashion.
Remove many unneeded components and change the type of others to HDR to speed up builds.
When tested with a modified srcbuild, RiscOS/Utilities/Release/srcbuild!5 there is no change to output binaries.
Also tested with RiscOS/Sources/Kernel!50 (merged) and RiscOS/Sources/Toolbox/Scale!1 (merged)