New approach for graph theory (continued)
New approach for graph theory (continued)

Main set.mm:
* theorem ~fzadd2 moved from JM's mathbox
* theorems ~2mpt20, ~wel2mpt2csbcl, ~el2mpt2cl, ~wrdexi, ~wrdeqi added

AV's mathbox:
* revision of definitions of WWalkSN and  ClWWalkSN and related theorems
* alignment of labels (suffix p for "properties", suffix bp for "basic properties")
* revision of ~wspthsn, ~iswspzhn, ~iswwlksnon, ~iswspthsnon, ~wwlknon, ~wspthnon

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