Several changes:

    - fixed a bug where the old session id was kept for file upload
    - added adjustSize() in WTableView
    - treeview-dragdrop example: restore numerical sorting
    - Several WGLWidget and 3D chart improvements and feature additions
    - Made WCssRule::selector() and WTemplate::templateText() virtual (#3217)
    - DomElement::removeAttribute() had no effect (#3271)
    - Fix alternating rowcolors out of sync for zoom != 100% (#1352)
    - port WServer::post() functionality to JWt
    - Fixed shift of 5 pixels (to left/top) on drag of WSlider
    - Fixed #2744 Segfault if slider range is 0 or 1
    - Updating slider so that disabled --> enabled transition works
    - Reimplement WServer::post() to enqueue action in session-specific queue