* utils/hbmk2/hbmk2.prg
+ added all public plugin API function with "hbmk_" prefix.
old "hbmk2_" prefixed ones still exist for compatibility,
but it's recommended to change them. "hbmk2" is only used
now as the tool's name, but internally it's uniformly
referred to as "hbmk".
* utils/hbmk2/examples/plug_tpl.hb
+ most "hbmk2" converted to "hbmk"