Add support for `@default`

[jwillemsen]

Add support for @default annotation

[jwillemsen]

Starter test at https://github.com/RemedyIT/taox11/tree/master/tests/idl4/default, not part of the test suite, test will fail when executed

[jwillemsen]

See #330, need to add support for default to more places like union, attributes, exceptions, etc

[jwillemsen]

Support added for union, exception, attributes (for ciaox11 generation)