Untargeted source generation

[DavidDudson]

Something like....

  def generate(f: File): List[Source] = ???
  def generate(f: String): List[Source] = ???
  def generate(): List[Source] = ???

This would allow scalagen to be used for things like

• Generating models from database schemas
• Generating models and visitors/listeners etc. from antlr files

Exactly what this will look like can be discussed later.