hook: fix full path imports on Windows (
issue1779)
Bottom portion fixes full path imports on source installs on Windows.
The top portion further fixes full path imports on binary installs.
Initial patch by Roman V. Kiseliov
diffstat: scale adds/removes proportionally to graph width
The previous method of scaling had a tendency to include graph lines that
went past the output width when the file with the most changes had a very
large number of changes.