TRQ-2828 momctl -q clearmsg doesn't seem to clear error messages permenantly

Fixed a problem in check_state where the local static message
variable would over-write the global message variable for
node health checks in between node check intervals.

Conflicts:

	src/resmom/linux/mom_mach.c
	src/resmom/mom_main.c
	src/resmom/mom_server.c

Conflicts:

	src/resmom/test/mom_server/scaffolding.c
	src/resmom/test/mom_server/test_mom_server.c

Conflicts:

	src/server/test/pbsd_main/scaffolding.c
TRQ-2831 use the vector size directly as it might change during the body of the loop.
TRQ-2460. Add two new entries to the accounting file.

Add total_execution_slots and unique_node_count to the accounting file.
total_execution_slots is the total number of processors, whether physical or logical, used by the job.
unique_node_count is the number of unique hosts the job used.
TRQ-1260: qdel clientretry support

Added clientretry feature as it works in qsub:
* -b <num> command line argument support;
* CLIENTRETRY configuration option support;
* PBS_CLIENTRETRY environment variable support.
Clientretry allows try to connect to the server in a loop during the
given time period.

Added 3-times retry to send the general command (delete task) to the
server as it implemented in qsub, see TRQ-2417.

Added unit test.

Removed server code duplicate from qsub.