Bug 60898 - XSSFColor's getARGB() method returns a wrong color value when a workbook...

Bug 60898 - XSSFColor's getARGB() method returns a wrong color value when a workbook has a custom indexed color

teach XSSFColor and most things that create instances about indexed colors.

Null is a valid value for IndexedColorMap instances - the existing built-in default colors are used.

Whenever a workbook style is accessible in the call hierarchy its color mappings are passed down now.

Thanks for the unit test in the issue, it now passes.

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1796359 13f79535-47bb-0310-9956-ffa450edef68