Typo in spaces.tex

Thanks to Yogesh More
http://stacks.math.columbia.edu/tag/025X#comment-585
Typo in algebra.tex
Typos in algebra.tex

Thanks to Wei Xu
http://stacks.math.columbia.edu/tag/02CA#comment-590
Add a reference to a lemma in proof in spaces.tex

Thanks to Yogesh
http://stacks.math.columbia.edu/tag/02WN#comment-599