Updating Begin and Execute for future plugins as well as Interfaces

[tws101]

1. Added additional input and output variables it begin command and execute to allow future plugins to handle Multiple Input and Output files. (Like adding external subtitle, audio tracks, or extracting subtitles or audio tracks)

2. Updated interfaces to accommodate change 1 typechecking.

3. Added Interface for type checking cospiredisolanguages

Updates 2 and 3 are for type checking and accuracy only