Add script that allows building the sphinx documentation using a virtualenv

doc/.gitignore

@@ -0,0 +1,2 @@
+build/*
+venv

doc/make-with-virtualenv.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+SOURCE="${BASH_SOURCE[0]}"
+while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
+  DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"
+  SOURCE="$(readlink "$SOURCE")"
+  [[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
+done
+DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"
+
+cd "$DIR"
+
+if [[ ! -d "venv" ]]; then
+	virtualenv venv
+	source ./venv/bin/activate
+	pip install -r requirements.txt
+else
+	source ./venv/bin/activate
+fi
+
+make SPHINXBUILD='venv/bin/python venv/bin/sphinx-build' $@

doc/requirements.txt

@@ -0,0 +1,32 @@
+alabaster==0.7.12
+Babel==2.9.0
+blockdiag==2.0.1
+breathe==4.24.1
+certifi==2020.11.8
+chardet==3.0.4
+docutils==0.16
+funcparserlib==0.3.6
+idna==2.10
+imagesize==1.2.0
+Jinja2==2.11.2
+MarkupSafe==1.1.1
+packaging==20.7
+Pillow==8.0.1
+Pygments==2.7.2
+pyparsing==2.4.7
+pytz==2020.4
+requests==2.25.0
+six==1.15.0
+snowballstemmer==2.0.0
+Sphinx==3.3.1
+sphinx-rtd-theme==0.5.0
+sphinxcontrib-applehelp==1.0.2
+sphinxcontrib-blockdiag==2.0.0
+sphinxcontrib-devhelp==1.0.2
+sphinxcontrib-drawio==0.0.12
+sphinxcontrib-htmlhelp==1.0.3
+sphinxcontrib-jsmath==1.0.1
+sphinxcontrib-qthelp==1.0.3
+sphinxcontrib-serializinghtml==1.1.4
+urllib3==1.26.2
+webcolors==1.11.1