slightly more helpful error message for missing db driver
remove bank methods from vault until we have actual bank support
more helpful/friendly startup error handling
embolden [vault] after creation; minor readme update
update changelog, readme
v1.5.0
add event-based vault creation system and interface for plugins to register their own AccountHolder types

sneak in attaching [vault] signs to chests directly
update changelog accordingly.
TownyAccountHolder friendly toString
v1.6.0-wip1