Select one of ten memories using paddle

[camilstaps]

With OPT_MORE_MEMORIES, it should be possible to key a digit using the paddle in the MEM_SEND_WAIT and MEM_ENTER_REVIEW states to select the memory, instead of using the rotary encoder.

[camilstaps]

This is only possible in MEM_SEND_WAIT state, because when reviewing it can be confusing (you may want to re-enter the memory, and not overwrite accidentally).