Fixed part of the walkthrough
Merge branch 'release-mindreader' of github.com:HazyResearch/deepdive into release-mindreader

Conflicts:
	doc/doc/basics/walkthrough/walkthrough.md
Updated basic tutorial
Merge branch 'release-mindreader' of github.com:HazyResearch/deepdive into release-mindreader

Conflicts:
	doc/doc/basics/walkthrough/walkthrough.md
Adding back some matteo's changes
Merge branch 'release-mindreader' of github.com:HazyResearch/deepdive into release-mindreader
Updated basic section of walkthrough