Miscellaneous processing tweaks
Add .mobi, .epub and unrar to .gitignore
Split comic2ebook.py main in two

Now has main() which initialises program and makeBook which does the
actual work.
Split comic2ebook.py main in two again

Now has main() which initialises the program and makeParser() which
sets up the option parser.
Use makeParser() for options in KCC_gui

KCC_gui now uses comic2ebook.makeParser() and setting global variable
in comic2ebook to handle options for ebook creation.
Use makeBook to create book from GUI

Call comic2ebook.makeBook() rather than comic2ebook.main()