add concept of dialect dependent config modifications/overrides

[jdavisclark]

There needs to be some kind of concept to allow the base mite configuration to be modified based on the dialect.

e.g. Migrations for dialect X use a different file extension, so a 'config provider', or something, for dialect X could override the migrationExtension setting.

e.g. could add support for config settings to enable/disable certain mite commands, which could be manipulated by different dialect config providers based on what might not be implemented.