Used the mods field in the attributes to indicate of "--" was specified in the header file. We
still save the units as "1" to keep it compatible with udunits. When outputting the variable
in data recording or variable server we check to see if the mods field for "--" is set. We
output "--" if the mods field is set. Also allowed "--" to persist in data products.
refs #254
Reorganized. Created a new top level include directory that will hold all of Trick's header files. Moved all of the Trick headers to this directory. Created a libexec directory that holds all of the executables that users don't need to execute directly. Changed all of the executables remaining in bin to start with "trick-". In the sim_services directories changed all source files to find the Trick headers in their new location. Since all of the include files are gone in sim_services, removed the src directories as well, moving all of the source files up a level. Moved the makefiles, docs, man, and other architecture independent files into a top level share directory. Renamed lib_${TRICK_HOST_CPU} to lib64 or lib depending on the platform we're currently on.
refs #63
