Add details on intersects and solutions to exercises.
Add notice on dependencies and link on build system.
Add link to dependencies in contrib guide. [ci skip]
Merge pull request #65 from wei2912/readme

Add details on dependencies and link to build system in README
Align text to 80 chars.
Merge pull request #64 from wei2912/chap2-sets

Chapter 2.1: Intuition of a Set
Undo benzrf's crap.
Merge branch 'unbenzrf' into develop
unundo benzrf's changes
Merge pull request #67 from pharpend/develop

unundo benzrf's changes
Add solutions to the union exercises.
Minor cosmetic edits, nothing much noteworthy.

I did comment out some of @wei2912's work, because I plan on redoing/editing it
later.
Comment out \end{document} in fdl.

This was causing the bibliography to not show up, and also causing issues when I
tried to fix #51.
FDL is now an appendix

This fixes #51.
Merge pull request #68 from pharpend/f-union-exercises

Add friendlier solutions to the union exercises, some cosmetic edits
Merge branch 'develop' into f-chapterstar

Conflicts:
	book/lysa.ltx
Merge pull request #69 from pharpend/f-chapterstar

Make FDL an appendix
Delete pandoc comment at top of introduction.

It's no longer relevant, as the formatting works just fine.
Redo the introduction.

@jesyspa, @beingbrown, and I discussed this in the IRC channel.
Fix \Cref to gfdl.