Create Docker container setup for the project

alignment.Dockerfile

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+# syntax=docker/dockerfile:1
+FROM ubuntu:focal
+ENV DEBIAN_FRONTEND=noninteractive
+RUN <<EOF
+# build SDL2
+# define installation directory
+mkdir SDL2
+export SDL2_INSTALLATION=/SDL2
+# clone SDL
+apt-get update -y
+apt install -y git build-essential
+git clone https://github.com/libsdl-org/SDL.git -b SDL2 && cd SDL && git checkout tags/release-2.26.2
+# build
+mkdir build && cd build && ../configure --prefix=$SDL2_INSTALLATION --enable-video-offscreen && make && make install
+EOF
+
+RUN <<EOF
+# build Irrlicht
+# install missing dependency
+apt-get update -y
+apt install -y zlib1g-dev libjpeg-dev libpng-dev libxi-dev cmake
+# clone irrlicht
+git clone https://github.com/EleutherAI/irrlicht && cd irrlicht && git checkout disable-x11
+# define lib paths
+export SDL2_INSTALLATION=/SDL2
+# build
+cmake . -DBUILD_SHARED_LIBS=OFF -DBUILD_HEADLESS=1 -DSDL2_DIR=$SDL2_INSTALLATION/lib/cmake/SDL2
+make -j8
+EOF
+
+RUN <<EOF
+# build minetest
+# install dependencies
+apt-get update -y
+apt install -y libzmqpp-dev libgmp3-dev protobuf-compiler libprotobuf-dev libzstd-dev libfreetype-dev libsqlite3-dev
+# clone minetest fork
+git clone https://github.com/EleutherAI/minetest
+git clone --depth 1 https://github.com/minetest/minetest_game.git minetest/games/minetest_game
+cd minetest
+git checkout cmake-SDL2-target-fix
+# compile protobuf
+cd hacking_testing
+./compile_proto.sh
+cd ..
+# define lib paths
+export SDL2_INSTALLATION=/SDL2
+export IRRLICHT_REPO=/irrlicht
+# build
+cd minetest
+cmake . -B build_headless_render -DCMAKE_BUILD_TYPE=Debug -DSDL2_DIR=$SDL2_INSTALLATION/lib/cmake/SDL2 -DIRRLICHTMT_BUILD_DIR=$IRRLICHT_REPO -DBUILD_HEADLESS=1 -DENABLE_SOUND=OFF -DRUN_IN_PLACE=1
+cmake --build build_headless_render
+EOF
+
+RUN <<EOF
+# Install Python packages and Xvfb
+apt-get install -y python3 python3-pip xvfb
+pip install numpy matplotlib gym zmq protobuf
+EOF
+
+WORKDIR minetest
+EXPOSE 30000
+CMD ["hacking_testing/server.sh"]