support for tproc mux

[meeg]

• Some backend changes to support a tProc multiplexer block we're testing
• Rework how we do register allocation: instead of the hard-coded mappings in ch_page() and sreg(), fill some mapping dictionaries at initialization. This will change the register page and number assignments for some firmwares, but if you were using ch_page() and sreg() your code will not change, and for the most part registers that were unused before will remain unused. The real purpose of this change is to allow us to allocate space more efficiently for firmwares with large numbers of generators.
• Tweaks to the formatting of the QickConfig printout, to hopefully make it easier to map gens/ROs to physical ports