2.7.5 "standalone" and "dispatch" targets

These targets are present in some subsets of HEAsoft, and allow a choice between the "standalone" build paradigm, in which each task is linked into its own binary, and the "dispatch" build paradigm, in which two or more related tasks are linked into one single binary. Normally, the "default" target selects the appropriate option, but on occasion it may be useful to invoke one of these targets directly, from a subset master Makefile. Using the "dispatch" target in a low-level Makefile by hand is not supported.