Added .gitignore: ignore __pycache__
Clean up RipTitle and ScanTiles, add Title class
Add --chapter_split flag.

The --chapter_split flag will enable chapter splitting. Titles that
contain multiple chapters will be split into a separate file for each
chapter.
Remove global variables.

Make all functions that look at the global variable "input" into methods
of a "DVD" class. This class takes the input as a constructor parameter.