Support for \include, more elaborate example, removal of .aux and .log

[runejuhl]

The makefile now also supports .tex files included with \include. Extended the example to include a reference (to generate .aux and .log files). Added functionality to remove these files when invoking "clean".

[ransford]

Awesome! Thanks! I'll have time to test and merge your patch this weekend. (Until today, I didn't even know that \include existed...)

[runejuhl]

You're welcome -- after all, you saved me from writing my own Makefile. The least I could do is extend the functionality a tiny bit!