Add tool for manipulating ROM relocation bitmaps

[Tom Seddon]

1. make relocatable ROM non-relocateable
2. extract bitmap (requires relocatable ROM + bitmap ROM)
3. add bitmap metadata (requires relocatable ROM to modify + bitmap ROM to append to + bitmap ROM bank number)
4. modify bitmap metadata (requires relocatable ROM + bitmap address + bitmap ROM bank number)

[Tom Seddon]

https://github.com/tom-seddon/beeb/tree/master/bin#tube_relocation