updated readme files for the macosx distribution
fix readline makefile
fix the way "run" detects an interrupted subjob so it can
signal an error.  Return code 512 is returned by a process
that exits with exit(2), so does not signal an interrupt.

I discarded the case where 1002 is returned, since it's a mystery.
Merge branch 'release-1.6' of github.com:Macaulay2/M2 into release-1.6
update debian changelog for the new version number
Merge branch 'release-1.6' of github.com:Macaulay2/M2 into release-1.6
punctuation
Merge branch 'release-1.6' of github.com:Macaulay2/M2 into release-1.6
fix interrupt handling, which has been broken for a long time
fix package CompleteIntersectionResolutions:
  a function was returning an error message instead of calling "error"
  some examples called "random" but not setRandomSeed
merge changes from release-1.6 into master