Consider supporting MOVE at toplevel

[tkers]

Right now move and friends are only available at run-time, or at compile-time from the host context. Consider supporting these words at compile-time in the target context too, in a way that they cross-copy memory from the host to the ROM.

The word mem, already works in a similar way: compiling data from host to ROM at the dictionary pointer.

Considerations:

• Referencing both memory spaces might be confusing to the user
• It's probably unlikely that you want to duplicate data in the ROM (with the amount of space available)
• It's probably more common that you want to copy data from the host to the ROM (when using meta definitions or host computations)