parallel: bug #42041: Implement $PARALLEL_JOBSLOT
bug #42041: Implement $PARALLEL_JOBSLOT {%}. tutorial + test.
Fixed bug #42363: --pipepart and --fifo/--cat does not work.
Makefile.am: should install distributed documentation if doc building tools does not exist.
Version upgrade.
src/Makefile.am: DISTCLEANFILES updated.