docker optimization

* move openwebrx project tools to a separate layer for lower download
  volume and faster builds
* use COPY instead of ADD
* COPY multiple files at once to reduce number of layers

docker/scripts/install-owrx-tools.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+set -euxo pipefail
+export MAKEFLAGS="-j4"
+
+function cmakebuild() {
+  cd $1
+  if [[ ! -z "${2:-}" ]]; then
+    git checkout $2
+  fi
+  mkdir build
+  cd build
+  cmake ${CMAKE_ARGS:-} ..
+  make
+  make install
+  cd ../..
+  rm -rf $1
+}
+
+cd /tmp
+
+STATIC_PACKAGES="libfftw3-bin"
+BUILD_PACKAGES="git autoconf automake libtool libfftw3-dev pkg-config cmake make gcc g++"
+apt-get update
+apt-get -y install --no-install-recommends $STATIC_PACKAGES $BUILD_PACKAGES
+
+git clone https://github.com/jketterl/js8py.git
+pushd js8py
+git checkout 888e62be375316882ad2b2ac8e396c3bf857b6fc
+python3 setup.py install
+popd
+rm -rf js8py
+
+git clone https://github.com/jketterl/csdr.git
+cd csdr
+# develop as of 2020-08-28
+git checkout 6d60d8c71f3484fd502174a2af27ceaaec6e60f8
+autoreconf -i
+./configure
+make
+make install
+cd ..
+rm -rf csdr
+
+git clone https://github.com/jketterl/digiham.git
+cmakebuild digiham 95206501be89b38d0267bf6c29a6898e7c65656f
+
+apt-get -y purge --autoremove $BUILD_PACKAGES
+apt-get clean
+rm -rf /var/lib/apt/lists/*