Keep up-right property for symbol elements (text etc.)

This issue came to me in an library symbol updating that I was working on.

I was adding "open collector" and others micro symbols to the part symbol to better inform the user / schematic read about the device properties. Doing so I realize that they come up-side-down.

Should be possible to define a group of element in a created symbol and attribute the keep-up-rigth property.

Warning: this may need a library file format update.

Application: KiCad
Version: 5.99.0-unknown-c3175b4~86~ubuntu16.04.1, release build
Libraries:
    wxWidgets 3.0.2
    libcurl/7.47.0 OpenSSL/1.0.2g zlib/1.2.8 libidn/1.32 librtmp/2.3
Platform: Linux 4.15.0-88-generic x86_64, 64 bit, Little endian, wxGTK
Build Info:
    Build date: Oct  3 2019 11:48:52
    wxWidgets: 3.0.2 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
    Boost: 1.58.0
    OpenCASCADE Community Edition: 6.8.0
    Curl: 7.47.0
    Compiler: GCC 5.4.0 with C++ ABI 1009

Build settings:
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=OFF
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON