Merge branch 'master' of https://github.com/HoTT/HoTT
Added links for Section 2.3 in contrib/HoTTBook.v
Merge branch 'master' of https://github.com/HoTT/HoTT

I'll use rebase next time, sorry.
more entries to HoTTBook.v
Merge branch 'master' of https://github.com/andrejbauer/HoTT

Conflicts:
	contrib/HoTTBook.v
Merge pull request #263 from marcbezem/master

Added links for Section 2.3 in contrib/HoTTBook.v

I am going ahead without a second pair of eyes, as it only affects contrib/HoTTBook.v