feat: bring back and adapt python bindings with rust core

* import python, try to adapt for rust

* add missing wrapper functions

* - try to write up how to build python bindings
- strike some unused functions from deltachat.h

* adjustments to make tox work

* try to run circle-ci with python build

* don't do docs

* running cargo test as well

* don't run cargo test anymore, that's done in other ci jobs

* also build docs

* don't run doxygen anymore

* subst C with Rust

* a try to get better wheels

Closes #41

python/README.rst

@@ -0,0 +1,161 @@
+=========================
+deltachat python bindings
+=========================
+
+This package provides bindings to the deltachat-core_ Rust -library
+which provides imap/smtp/crypto handling as well as chat/group/messages
+handling to Android, Desktop and IO user interfaces.
+
+Installing pre-built packages (linux-only)
+==========================================
+
+If you have a linux system you may install the ``deltachat`` binary "wheel" package
+without any "build-from-source" steps.
+
+1. `Install virtualenv <https://virtualenv.pypa.io/en/stable/installation/>`_,
+   then create a fresh python environment and activate it in your shell::
+
+        virtualenv -p python3 venv
+        source venv/bin/activate
+
+   Afterwards, invoking ``python`` or ``pip install`` will only
+   modify files in your ``venv`` directory and leave your system installation
+   alone.
+
+2. Install the wheel for linux::
+
+        pip install deltachat
+
+    Verify it worked by typing::
+
+        python -c "import deltachat"
+
+
+Installing a wheel from a PR/branch
+---------------------------------------
+
+For Linux, we automatically build wheels for all github PR branches
+and push them to a python package index. To install the latest github ``master`` branch::
+
+    pip install -i https://m.devpi.net/dc/master deltachat
+
+
+Installing bindings from source
+===============================
+
+If you can't use "binary" method above then you need to compile
+to core deltachat library::
+
+    git clone https://github.com/deltachat/deltachat-core-rust
+    cd deltachat-core-rust
+    cargo build -p deltachat_ffi --release
+
+This will result in a ``libdeltachat.so`` and ``deltachat.h`` file
+in the ``deltachat_ffi`` directory. These files are needed for
+creating the python bindings for deltachat::
+
+    cd python
+    CFLAGS=I`pwd`/../deltachat-ffi pip install -e .
+
+You then need to set the load-dynamic-library path in your shell::
+
+    export LD_LIBRARY_PATH=`pwd`/../target/release
+
+so that importing the bindings finds the correct library::
+
+    python -c 'import deltachat ; print(deltachat.__version__)'
+
+This should print your deltachat bindings version.
+
+.. note::
+
+    If you can help to automate the building of wheels for Mac or Windows,
+    that'd be much appreciated! please then get
+    `in contact with us <https://delta.chat/en/contribute>`_.
+
+
+Code examples
+=============
+
+You may look at `examples <https://py.delta.chat/examples.html>`_.
+
+
+Running tests
+=============
+
+Get a checkout of the `deltachat-core github repository`_ and type::
+
+    cd python
+    export CFLAGS=I`pwd`/../deltachat-ffi
+    export LD_LIBRARY_PATH=`pwd`/../target/release
+    pip install tox
+    tox
+
+If you want to run functional tests with real
+e-mail test accounts, generate a "liveconfig" file where each
+lines contains test account settings, for example::
+
+    # 'liveconfig' file specifying imap/smtp accounts
+    addr=some-email@example.org mail_pw=password
+    addr=other-email@example.org mail_pw=otherpassword
+
+The "keyword=value" style allows to specify any
+`deltachat account config setting <https://c.delta.chat/classdc__context__t.html#aff3b894f6cfca46cab5248fdffdf083d>`_ so you can also specify smtp or imap servers, ports, ssl modes etc.
+Typically DC's automatic configuration allows to not specify these settings.
+
+You can now run tests with this ``liveconfig`` file::
+
+    tox -- --liveconfig liveconfig
+
+
+.. _`deltachat-core github repository`: https://github.com/deltachat/deltachat-core-rust
+.. _`deltachat-core`: https://github.com/deltachat/deltachat-core-rust
+
+
+Building manylinux1 wheels
+==========================
+
+Building portable manylinux1 wheels which come with libdeltachat.so
+and all it's dependencies is easy using the provided docker tooling.
+
+using docker pull / premade images
+------------------------------------
+
+We publish a build environment under the ``deltachat/wheel`` tag so
+that you can pull it from the ``hub.docker.com`` site's "deltachat"
+organization::
+
+    $ docker pull deltachat/wheel
+
+The ``deltachat/wheel`` image can be used to build both libdeltachat.so
+and the Python wheels::
+
+    $ docker run --rm -it -v $(pwd):/io/ deltachat/wheel /io/python/wheelbuilder/build-wheels.sh
+
+This command runs a script within the image, after mounting ``$(pwd)`` as ``/io`` within
+the docker image.  The script is specified as a path within the docker image's filesystem.
+The resulting wheel files will be in ``python/wheelhouse``.
+
+
+Optionally build your own docker image
+--------------------------------------
+
+If you want to build your own custom docker image you can do this::
+
+   $ cd deltachat-core # cd to deltachat-core checkout directory
+   $ docker build -t deltachat/wheel python/wheelbuilder/
+
+This will use the ``python/wheelbuilder/Dockerfile`` to build
+up docker image called ``deltachat/wheel``.  You can afterwards
+find it with::
+
+   $ docker images
+
+
+Troubleshooting
+---------------
+
+On more recent systems running the docker image may crash.  You can
+fix this by adding ``vsyscall=emulate`` to the Linux kernel boot
+arguments commandline.  E.g. on Debian you'd add this to
+``GRUB_CMDLINE_LINUX_DEFAULT`` in ``/etc/default/grub``.