The Stacks project

Fixed small typos

Grassmannian

Started tags infrastructure

	new file:   scripts/add_tags.py
	modified:   scripts/functions.py
	new file:   tags/initial_tags
	new file:   tags/tags

Changed the index to at least have an alphabetized list of terms defined
in the project. Thanks Cathy!

	modified:   algebra.tex
	modified:   categories.tex
	modified:   constructions.tex
	modified:   exercises.tex
	modified:   fpqc-descent.tex
	modified:   groupoids.tex
	modified:   homology.tex
	modified:   hypercovering.tex
	modified:   modules.tex
	modified:   morphisms.tex
	modified:   properties.tex
	modified:   schemes.tex
	modified:   scripts/functions.py
	modified:   scripts/make_index.py
	modified:   sheaves.tex
	modified:   simplicial.tex
	modified:   sites.tex
	modified:   spaces.tex
	modified:   topology.tex

Added stuff on Proj of a graded ring

	modified:   algebra.tex
	modified:   constructions.tex
	modified:   modules.tex
	modified:   properties.tex
	modified:   schemes.tex

Started more seriously on schemes

	new file:   constructions.tex
	modified:   modules.tex
	new file:   morphisms.tex
	new file:   properties.tex