The Stacks project

Fix typo in examples-stacks

Thanks to ykm
https://stacks.math.columbia.edu/tag/03YM#comment-5518

Introduce macros for moduli stacks/spaces

Not sure this is a good idea but at least for the
different versions of Pic it was necessary to more
clearly distinguish especially in statements of
lemmas (bc of the italics that is used there by
LaTeX).

LaTeX

Introduced a macro

\def\QCoh{{\textit{QCoh}}}

and replaced almost all occurences of \textit{QCoh} by \QCoh. There are
still some places where we use \textit{QCoh}, namely in the chapter
on examples of stacks. This is because the meaning there is different;
it indicates a category fibred in groupoids over Sch and not the notational
gadget that takes a ringed topos and spits out its category of
quasi-coherent modules.

Unify notation \textit{QCoh}

LaTeX: \Sch

	Introduced a new macro

	\def\Sch{\textit{Sch}}

	and replaced all the occurences of \textit{Sch} with \Sch.

QCoh satisfies the axioms of a stack

All examples of stacks in one chapter

	Added examples-stacks.tex to the project
	Moved the examples in algebraic.tex to examples-stacks.tex
	Moved the examples in examples.tex to examples-stacks.tex
	Changes Makefiles, scripts, etc.

All examples of stacks in one chapter

	Added examples-stacks.tex to the project
	Moved the examples in algebraic.tex to examples-stacks.tex
	Moved the examples in examples.tex to examples-stacks.tex
	Changes Makefiles, scripts, etc.

Algebraic stacks: Elaborate on example.

	Also introduce a method for replacing a ``big'' stack by a small
	one.

Tags: added new tags

Algebraic Stacks: Making the definition work.

	This is a rather large set of changes. It turns out that we need
	to repeat some of the work done in the setting of schemes in the
	setting of algebraic spaces. We can do this as we go along, but
	we need to have the framework in place with some example
	sections. Hence added to the project are a chapter on topologies
	on algebraic spaces and a chapter on descent and algebraic
	spaces. We further need to add much more material to the section
	on morphisms of algebraic spaces, since right now we do not even
	cover the notion of a smooth morphism of algebraic spaces.

	Of course most of this is a simple matter of pointing out the
	relevant results on schemes. Still...