Intuitionize necon* in set.mm
Intuitionize necon* in set.mm

- add con4biddc (analogue to con4bid for decidable propositions)

Rewrite proofs for theorems which do hold for all propositions
but which require different proofs: necon3ad, necon3bd, necon3ai,
necon3bi, necon2ai, necon2ad

Replace various theorems with ones which are the same but with
decidability conditions added (analogous to con1dc, condc, etc):
- replace necon1ai with necon1aidc
- replace necon1bi with necon1bidc
- replace necon1i with necon1idc
- replace necon1abii with necon1abiidc
- replace necon1bbii with necon1bbiidc
- replace necon1abid with necon1abiddc
- replace necon1bbid with necon1bbiddc
- replace necon2abii with necon2abiidc
- replace necon2bbii with necon2bbiidc
- replace necon2abid with necon2abiddc
- replace necon2bbid with necon2bbiddc
- replace necon4ai with necon4aidc
- replace necon4i with necon4idc
- replace necon4ad with necon4addc
- replace necon4bd with necon4bddc
- replace necon4d with necon4ddc
- replace necon4abid with necon4abiddc
- replace necon4bbid with necon4bbiddc
- replace necon4bid with necon4biddc
- replace necon1ad with necon1addc
- replace necon1bd with necon1bddc
- replace necon1d with necon1ddc

metamath/set.mm,metamath/set.mm,metamath/set.mm