pretty-printer: consistently print nested tuples with (,) syntax

[amosr]

The tuple printer p_tmTuple was calling p_tmEq for values inside the tuple, but p_tmEq was printing nested tuples as Mktuple2. I've added a check inside p_tmEq to call back to the tuple printer, which matches how dependent tuples are printed too.

[mtzguido]

Nice Amos, thank you!