Fix: Changed handling of short hex colours.

Just a small change to yield more accurate colours when the user supplies a 3 character hex code.  

The existing code would convert #cde into #cdecde, which is actually a different colour when compared side by side.  This modified bit of code produces #ccddee, which shows up as an identical colour to the original 3 character version.  Tested in Firefox and Chrome - hopefully IE uses the same colour rendering logic for its css, too.