issue #21, fixed ⍺!⍵ for fractional args

Stupid of me not to include a doctest for that
Function "factorial()" did not exist

There are still more cases to be covered
fixed monadic ⍨ (commute), issue #22

Apparently, f⍨⍵ is supposed to mean {⍵f⍵}, not just {f⍵}
fixed prio of prefix vs postfix adverbs, issue #22
Merge remote-tracking branch 'upstream/master'
Make code font less enormous.