LibEdit: Editing arc points does not work

[Seth Hillbrand]

Steps
1) Open LibEdit, make a new symbol
2) Draw an arc
3) Select it to show the edit points
4) Move an edit point

At this point the visible arc is unchanged by the arc points are changed and it becomes hard to re-select the arc. Moving the arc center point seems to move the arc but moving the end points does not affect the image.

Application: LibEdit
Version: (5.1.0-1152-gc9ccd8a64), release build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.64.0 OpenSSL/1.1.1c zlib/1.2.11 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.5) libssh2/1.8.0 nghttp2/1.36.0 librtmp/2.3
Platform: Linux 4.19.0-5-amd64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
    Boost: 1.67.0
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.64.0
    Compiler: GCC 8.3.0 with C++ ABI 1013

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

[Jeff Young (jeyjey)]

I've rewritten the way arcs are edited. If folks like it we can consider this "fix committed"; otherwise it'll be back to the drawing board. ;)

[Jeff Young (jeyjey)]

Not a lot of comments on this, but what I have seen have been uniformly positive so I'll mark this "Fix Committed" for now.

[Seth Hillbrand (sethh)]

@jeyjey - I forgot to add my positive comments: "Awesome! Nicely done!" :)

I'll see if I can port this handling to pcbnew as well. I just did a DXF export of a curved board and _every_ endpoint was disconnected by fractional units.