Adds l.c.i. morphisms

l.c.i. morphisms are stable under composition, and fpqc local. They are stable under flat base change.
(And as far as I can see they are not stable under arbitrary base change, but I have not thought about a counterexample.
Adds tag for l.c.i. morphisms
Corrects the tag for l.c.i. morphism
Corrects tags for l.c.i. morphism
Merge pull request #5 from jcommelin/patch-1

Adds l.c.i. morphisms (with correct tags)