Changed font for exponents in plot labels, added new address for tickets (now at github).
Merge branch 'master' of https://github.com/ibell/coolprop
Merge branch 'master' into unitfied

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
fix to gitrevision.h

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>