First phase of major refactoring to separate out generic libs for dADL (will be renamed ODIN), BMM, DT_XX classes from ADL / Archetype app.

dADL (ODIN) now has its own new primitive type TERMINOLOGY_CODE to represent what CODE_PHRASE is in the AOM. This necessitated a smarter type conversion facility in DT_OBJECT_CONVERTER.

Finalised (or close) the replacement of Billboard with per-object error messages using ERROR_ACCUMULATOR.
Further refactoring to enable bmm_demo app to compile with no dependence on any ADL, AOM or ARCHETYPE classes.
Various file moves and directory restructuring