The Stacks project

Fix signs in section on Cech cohomology of complexes

	The Cech complex of a complex of abelian sheaves F^* has terms

		C^p(U, F^q)

	and p is the first index. Hence the differential, according to
	our general conventions should be

		Cech differential + sign * differential of F^*

	This simplifies many of the calculations. We also added a script
	which checks the signs for the cup-product.

Started tags infrastructure

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

Tiny bit more on Cech cohomology
Usual problem of not being able to find a suitable reference for
comparing alternating to Cech maps

	modified:   cohomology.tex

Existence of injective abelian sheave on spaces
Started writing about Cech cohomology on spaces

	modified:   cohomology.tex
	modified:   homology.tex
	modified:   injectives.tex
	modified:   sheaves.tex