[SUGGESTION] Pretty-printing custom unit types

[apache2]

When pretty-printing, poke doesn't use the original unit name of struct fields:

#!!# unit U32bits = 4*8;
#!!# type Foo = struct { offset< int, U32bits> how_many; };
#!!# Foo{}
Foo {
  how_many=0x0#32
}
Here it prints #32 instead of #U32bits.

If how_many was an offset<int, B> it would however print how_many=0x0#B

Is this something we can fix without too much work?