Minor monthly bugfix release with a new RainbowAstro mount driver and improved pier side simulation.

Minor bugfix release with some highlights.

+ New RainbowAstro Mount driver.
+ New Simulated Pier Side option for all mounts.
+ Added iOptron GEM45 support. (#1041)
+ Added *preliminary* support for iOptron iPolar. (#1043)
+ Update Celestron GPS Guide (#1048)
+ Bug fix: meridian flip working for longer polling intervals (#1042)
+ Update Celestron GPS Guide (#1048)
+ Added recording the absolute position of the focuser to the FITS header (#1052)
+ Fix enabling/disabling DMFC properties and remove dead code (#1050)
+ Enable saving/loading backlash steps and fix motor type select (#1055)