Add lower left corner of the page as possible coordinate origin
Description
At the moment there's no side-effect free way to have a normal mathematical coordinate system (Y axis grows upwards) where the page would be in the positive side.
I suggest adding the lower left point of the page as the possible origin. I don't know how difficult it is because it has to be calculated relative to the page size. It would also change if the page size is changed. But it shouldn't be very different from using the movable drill or grid origins.
KiCad Version
Application: Pcbnew
Version: (5.99.0-3036-gf9e379c82), debug build
Libraries:
wxWidgets 3.0.4
libcurl/7.68.0 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh/0.9.3/openssl/zlib nghttp2/1.40.0 librtmp/2.3
Platform: Linux 5.4.0-42-generic x86_64, 64 bit, Little endian, wxGTK
Build Info:
Date: Aug 28 2020 09:44:14
wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
Boost: 1.71.0
OCE: 6.9.1
Curl: 7.68.0
Compiler: GCC 9.3.0 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=OFF
KICAD_USE_OCE=ON
KICAD_SPICE=OFF
KICAD_STDLIB_DEBUG=OFF
KICAD_STDLIB_LIGHT_DEBUG=OFF
KICAD_SANITIZE=OFF