Updated Prime Variables table

[Joe Horn]

The list of Prime's built-in app variables has changed since rev 8151, so my online alphabetical table of HP Prime Reserved Variables has been updated to match rev 10637.

The most notable changes are:

• The apps that support graphing now allow you to select a background image. The new app variables associated with that feature are: ImageName, ImageDisplay, ImageOpacity, ImageXmin, ImageXmax, ImageYmin, and ImageYmax.

• The Finance app's vars which were formerly called "Results" vars are now called "TVM" vars by the menu system.

• The Triangle Solver's "Rect" var has been renamed "TriType".