build diagnostic improvements for server-side GL
Merge commit 'github/master'
Merge commit 'github/master'
Several changes:

    - use WStandardItem::setItemPrototype() to accept numeric data in models (#2717)
    - install DomElement.h and EscapeOStream.h (#2684)
    - use rpath for macsox builds (#2705)
    - implemented WTextEdit::setEnabled() and setReadOnly()
    - Removed obsolete Safari workaround (#2701)
    - Sending mail: report success/failure as return value for send()
    - added WTemplate::renderTemplateText error reporting
    - Fixed bestMatch logic in RequestHandler (#2694)
    - Added automatic redirect following to HTTP client (#2605)
    - Fix Http client: Change empty path into /
    - WDoubleSpinBox: decimalPoint and groupSeparator support (#2363)