First syntax goal: functions

[TimvdLippe]

To get a basic syntax definition, our first goal will be to correctly parse functions. A function typescript consists of the following:

• function keyword
• name
• parameter list (optional) (each parameter also has a type annotation)
• optional return type (none => void)
• zero or more statements

To be able to parse functions, we therefore rely on some easy type definitions, but it is similar to how we did the MiniJava definitions.

[TimvdLippe]

So we did this already in https://github.com/MetaBorgCube/metaborg-typescript/commit/990ba689eb77a49aa9fc92dc124969e2f16016e5 :tada: