have_copy dedups code in the ultimate case $CMD statement

have_copy -n $path fails (with an appropriate complaint)
iff test -d $path; have_copy -y $path does the same
iff ! test -d $path.
cl, ro commands have common implementation
y2m sticks to $PWD, $Y2MBASE is no more
y2m: command dispatch redone, cl needs no handholding

* the clone command does away with the convoluted computation
  of $ORG, and does not need any maintenance for irregular
  repository names.

* y2m has had a handful of coauthors, everybody is recorded
  in the revision history.
Merge pull request #11 from roman-neuhauser/dispatch-redone

Dispatch redone