Fix licensing issues

.gitlab-ci.yml

@@ -1,26 +0,0 @@
----
-Debian 9:
-  stage: build
-  image: debian:stretch
-  script:
-    # deltachat-core needs a later version of meson, fortunately it's in stretch-backports
-    - echo 'deb http://httpredir.debian.org/debian/ stretch-backports main' > /etc/apt/sources.list.d/stretch-backports.list
-    - apt update
-    # libetpan
-    # FIXME: libetpan 1.16 is available in Debian, but we need 1.17+: https://github.com/deltachat/deltachat-core/issues/157
-    - apt install --no-install-recommends -yy -t stretch-backports build-essential autoconf automake libtool libdb-dev libexpat1-dev libsasl2-dev libssl1.0-dev
-    - cd vendor && tar -xvzf libetpan-1.8.tar.gz && cd libetpan-1.8 && ./autogen.sh && ./configure && make && make install && cd ../..
-    - cp /usr/local/lib/libetpan.so libetpan.so
-    # deltachat-core
-    - apt install --no-install-recommends -t stretch-backports -yy meson ninja-build pkg-config zlib1g-dev liblockfile-dev libsqlite3-dev libsasl2-dev libssl1.0-dev libbz2-dev
-    - cd vendor && tar -xvzf deltachat-core-0.41.0.tar.gz && cd deltachat-core-0.41.0 && mkdir builddir && cd builddir && meson && ninja && ninja install && cd ../../..
-    - cp /usr/local/lib/x86_64-linux-gnu/libdeltachat.so libdeltachat.so
-    # purple-plugin-delta
-    - apt install --no-install-recommends -t stretch-backports -yy libpurple-dev libglib2.0-dev
-    - make
-  artifacts:
-    paths:
-      - libetpan.so
-      - libdeltachat.so
-      - libdelta.so
-

README.md

@@ -24,17 +24,23 @@ can view specific progress on [the issue board](https://gitlab.com/lupine/purple
 
 ## Build
 
-Very basic instructions at present. First, `deltachat-core` isn't packaged, so
-you'll need to build and install it according to
-[these instructions](https://github.com/deltachat/deltachat-core/blob/master/README.md#build).
+There are some licensing issues at present, so you shouldn't build this plugin.
 
-Now, you'll need some other build dependencies:
+`deltachat-core` vendors openssl, unconditionally links it, and is MPL-licensed.
 
-```
-sudo apt install build-essential libpurple-dev libglib2.0-dev
-```
+`purple-plugin-delta` is GPLv3 without the [OpenSSL exemption](https://people.gnome.org/~markmc/openssl-and-the-gpl.html)
 
-Finally, run `make` to create a `libdelta.so` file.
+`libpurple` itself is GPLv2 without the OpenSSL exemption.
+
+`deltachat-core-rust` may make OpenSSL optional, so linking against that version
+would be fine.
+
+Linking against a patched / changed `deltachat-core` that disregards vendored
+OpenSSL and uses GnuTLS instead would also be fine.
+
+There's no point to `purple-plugin-delta` adding the OpenSSL exemption because
+`libpurple` lacks it, and in any event, it will be unnecessary with the next
+major version of OpenSSL. So, time should resolve this for us one way or another.
 
 ## Use