Hi,

It would be great to have a better control over which files will be build. Right now make epub will build both epub and pdf, which is a bit misleading. Something like this would be awesome:

• make all - make all available book formats (epub and pdf for now)
• make epub - make epub only
• make pdf - make pdf only (I guess by removing the epub file after the pdf is created)

I can create a pull request for that.

What do you think?