Preprocessor

Responsible for all scala-source-code-munging that happens within the Ammonite REPL.

Performs several tasks:

• Takes top-level Scala expressions and assigns them to res{1, 2, 3, ...} values so they can be accessed later in the REPL

• Wraps the code snippet with an wrapper object since Scala doesn't allow top-level expressions

• Mangles imports from our ammonite.util.ImportData data structure into a source String

• Combines all of these into a complete compilation unit ready to feed into the Scala compiler