Custom command aliasing

This patch release adds the appropriate mechanisms to alias custom
commands for ease-of-development. This allows one custom command to
simply be defined as a second name for another custom command within
it's own class (equalTo, startsWith, targeted, multitargeted).

Note that at this time an alias target cannot itself be an alias. If
this deficiency ever presents actual damage in real configurations
(perhaps this is likely when live reconfiguration comes into play), I
will add in alias-dereference loops to handle this situation.