vcs: Remove all mention of use of -ve revision numbering. The introduction seems forced. It's a neat trick, but doesn't fit into the flow of things. Now introducing revision numbering with the need to take diffs between particular commits. Also mention -v and -l parameters to the log command.

\documentclass{article}
\title{A Glimpse at Scipy}
\author{FOSSEE}
date{2010}
\begin{document}
\maketitle
SciPy is open-source software for mathematics, science, and
engineering.   
\end{document}