Description

This defines a basic process for including auto-correcting/updating of datafiles etc. when users upgrade to a new binary version.

Changes

main.go now defines VERSION - this should match release versions
internal/migration/ code foor migration purposes.
migration code is invoked in main.go before datafiles etc. are loaded (except for config)
fixes a small error in training room script
migration creates a backup of datafiles and restores on any errors
flag --version can be used when running gomud to display version and quit
version set to 0.9.1