main methods not counted

[ratefuchs]

we need to report an error if we have zero or multiple mains.

[djrieger]

Multiple mains are already accounted for when checking for duplicate method names in ast::MethodDeclaration::collectDefinition. Reporting zero mains should be easy once MethodTable is usable.

[ratefuchs]

Multiple mains in one method is already an error, but it is also forbidden to have multiple mains in the whole program.