Wed Aug 8 14:42:05 EDT 2018

Indexed muxes

Now, how to express larger multiplexers?  These could be expressed as
nested if statments, but MyHDL will generate a case statement if it
sees successive ifs.

Maybe it is time to handle nested ifs differently.

EDIT: See SeqLib.index

Straightforward with zero-extended array, and recursive expansion
based on bits of the indexing word.