update to new upstream stable release (first officially-stable release since 3.1)
    
    drop documentation subpackage, because upstream does not yet have a pdf
    for 4.1; see docs online at http://rawtherapee.com/blog/documentation and
    http://rawpedia.rawtherapee.com/
    
    no need to include COMPILE.txt in binary package, but do incliude
    RELEASE_NOTES.txt