Added getUserAgent() to IFDocumentHandler (implemented by all implementations already).

Added getUserAgent() to IFDocumentHandler (implemented by all implementations already).
Full image support for PSPainter.
PostScript output now uses the ImageHandler facility (IF and renderer) for both inline (ImageHandler interface) and form image production (PSImageHandler interface). No more hard-coded image flavor list.
Resource optimization extended so images that are only used once are inlined to lower memory requirements in the PostScript VM.
Added test cases using Commons' DSC parser to verify the new functionality.
Added IFDocumentHandler override possibility in FOUserAgent (just like for FOEventHandler and Renderer).
Subject support for PDF output.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/branches/Temp_AreaTreeNewDesign@727405 13f79535-47bb-0310-9956-ffa450edef68