Changes to 1.0.10

* Allow changing variable names for all plotting functions
* Add SlopefieldTicks, VectorfieldTicks, LinePlotVariableNames, and
  SurfacePlotVariableNames, parameters
* Add AskButtons interactive function
* CHANGE: spelling fix: AuxiliaryUnitMatrix doesn't have two l's
* Support for setting legend on LinePlotDrawLine with a "legend" parameter
* Allow comparisons (== and !=) with null, treating it as an empty matrix
* Uses GIO instead of GnomeVFS (Jan de Groot)
* Fix compilation without gtksourceview (thanks to Joe Sapp for pointing this
  out)
* Fix some crashes in plotting code
* Allow slopefield solutions to leave plot window by a small fudge factor.
* Fix zooming plots so that we can zoom by moving mouse in any direction
* Fix compilation with newer sealed vte (Vincent Untz)
* Fix up some typos in the documentation (Christian Kirbach, me)
* Translation updates (Christian Kirbach, Jorge González, Andrej Žnidaršič,
  Kjartan Maraas, Petr Kovar, Mario Blättermann, Fran Diéguez, Matej Urbančič,
  Andrej Žnidaršič, Marek Černocký, me)

* For some of the changes the author (Jiri) was partially supported by
  NSF grant DMS 0900885 and the University of Illinois at Urbana-Champaign