Add file sim-hload.c - generic load for hardware only simulators.
Review each simulators sim_open, sim_load, sim_create_inferior so that
they more closely match required behavour.
that image properties such as endianness can be checked.
More strongly document the expected behavour of each of the sim_*
interfaces.
Add default endian argument to simulator config macro
SIM_AC_OPTION_ENDIAN. Use in sim_config.
