Warn on names that don't follow convention

[jminer]

When parsing an IDL file, warn when a protocol/record/field name does not follow convention. There could be a annotation/property that changes what the naming convention should be, say @recordNaming("PascalCase") or @recordFieldNaming("snake_case") or @enumSymbolNaming("SCREAMING_SNAKE_CASE").

This warning would kind of be a nice usecase for an AST, so that the warning could be emitted after parsing, yet the line number still be reported. But I don't think it is enough reason to add an AST, so I'll just add the warning to the parser.