Add checks for programs which are required for the test suite to run. All prerequisite programs are checked for existance, and if any are missing, a list of missing programs is printed, and the test suite is aborted. All programs currently used in the tests, except those in core-utils, are checked.

removing b
this update spans a branch affecting the following files:
 b
aborting update spanning branches!
(use update -m to merge across branches or -C to lose changes)