Parses a color property and regurns a ARGB code (FFRRGGBB).

In the future, this would be the place to support color names such as "red", etc. Also, XLSX has "indexed" colors, see https://msdn.microsoft.com/en-us/library/documentformat.openxml.spreadsheet.indexedcolors(v=office.14).aspx for a list.

Examples

iex> Elixlsx.Color.to_rgb_color("#aa5533")
"FFAA5533"