Several changes:

    - fix websocket-based widgetset application reloading giving restart popup
    - remove redundant setPopup() calls and unnecessary z-index styles
    - wthttp: fix HTTP header value length error
    - win32: add version information to Wt when building DLLs.
    - WDatePicker: revert to a plain container for layout
    - current mariadb version does not have mysql_library_init