Update for ee* changes from set.mm
Update for ee* changes from set.mm

Rename ee21 to syl6ci
Rename ee23 to syl10
Rename ee10 to mpisyl
Rename ee12an to syl6an
Remove ee22, which was identical to syl6c

Remove ee02 which is in a mathbox in set.mm and is unused in
iset.mm.

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