Add the useful intersection of sanitize.py

From stagestosaturn.git and chariotsforapollo.git
Add a skeleton EPUB structure and Makefile

Use style="width: 100%" instead of width="100%" on the cover image,
since that makes cover.html validate and still works.
Merge common infrastructure from epubbase

Conflicts:
	.gitignore
	Makefile
	OEBPS/.gitignore
	OEBPS/content.opf
	OEBPS/toc.ncx
	cover.html
	sanitize.py
Move stylesheet.css out from OEBPS

The EPUB has been verified functionally identical to that of
commit 6713bc23b0d4c9e22c530a224ef6821a1cab4ac2.