Draft: Multi injectors many

Use a number of threads to do the injection. This is more SWIFT like.

Also see !1 (closed).

Result seems to be a small improvement in the injection fidelity, but does not address the problem with a lot of injections in the early parts. The run time is also slightly improved.

Makefile

@@ -3,7 +3,7 @@ CFLAGS = -g -O0 -Wall
 
 all: swiftmpistepsim
 
-swiftmpistepsim: swiftmpistepsim.c mpiuse.c mpiuse.h atomic.h cycle.h clocks.h clocks.c
+swiftmpistepsim: swiftmpistepsim.c mpiuse.c mpiuse.h atomic.h cycle.h clocks.h clocks.c Makefile
 	$(CC) $(CFLAGS) -o swiftmpistepsim swiftmpistepsim.c mpiuse.c clocks.c -I/usr/include/mpi -lmpi -lpthread
 
 clean: