Number theory misc.
Number theory misc.

* ~gcdzeq moved from AV's mathbox to main set.mm ( generalization of ~ gcdeq)
* new theorems ~isevengcd2 and ~isoddgcd1
* Section "Proth's theorem" moved into section "Number theory (extension)" (proth's theorem ~proththd does not depend on definition of symbol ` Odd ` anymore).

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