Excel 2007 and later allows for more than 3 Conditional Formatting rules per sheet, so change our hard limit to logging a compatibility warning. Test file from Pau Coma Ramirez from bug #56482

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1591959 13f79535-47bb-0310-9956-ffa450edef68