Module: conf-based system for Vault module registration

[eledhwen]

Consider adding a conf-based system for module registration, most common use-case being the registration of modules on the default parser.

As it stands Vault requires the developer to handle module registration somewhere, most likely in a static block in the Main class, which can be a tad confusing at first glance, but also a bit of a pain to manage if several contexts coexist (most common issue being the program Main vs. tests).

It would be easy enough to add a module registration configuration, probably also allowing the developer to specify which file to use if a specific context requires a switch (could be handled via system properties and/or env vars).

The file itself could be a very basic conf file or a vault yml file (vanilla Vault, that is). First one offers extremely simple syntax as a plus, but limits capability if some modules require configuration (ctor arguments for instance).