Add support for default values for function parameters

[DanielKamkha]

Modern programming languages (e.g. Kotlin, Swift, Dart) provide a functionality of specifying default values for function parameters. For languages that do not support this feature (Java, C++, current version of LimeIDL), it still can be emulated by re-declaring a method overload with a different signature.

The same feature on IDL level for Gluecodium is what many users already expect (being mislead by LimeIDL's Kotlin-like synax). It is technically feasible to implement in Gluecodium and it can reduce the unnecessary duplication the "emulation" approach creates for such methods.