add header files to EXTRA_DIST list

allows 'make distcheck' to run cleanly
reformat TESTS/check_PROGRAMS variables

List test programs in separate variable (TEST_PROGS) so that they don't
have to be listed in two places (TESTS and check_PROGRAMS) -- had already
left one program out of TESTS.
reformat usage message
reformat test macros
add itertol and maxiter command-line options
reformat default command-line arguments

Define defaults in separate header file and have mm_get_cl_args set
defaults, rather than leaving it to mpi_makemap.
add main iteration loop
add output filename prefix c-l option
add calc_chisq function and test
Create "global.h" for common declarations

All header files include "global.h". File includes:
* config.h
* UNUSED definitions
add mpi call to sum chisq over processes
change description of options in prologue
change status messages (only root reports iter #)
add convergence checking
mark iteration logic completed