Palette consistency for terminals. Added template for Terminator.

Hi,

Found this project today, very cool. This pull-request includes the following:

  * Corrected the background colour for Geany Dark template.
  * Modified palettes for MATE Terminal and GNOME Terminal. They are now correct and consistent with other terminals/shells.
  * Add Light templates for MATE Terminal, GNOME Terminal and Geany.
  * Add Dark and Light templates for Terminator.

Regards, Martin.