Add doxygen to build system

doxygen/build-doxygen.sh

@@ -0,0 +1,20 @@
+#!/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 && 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 && pwd )"
+cd "$DIR"
+
+export PROJECT_NUMBER=`git describe --tags`
+
+if [ $# != 1 ]; then
+	export OUTPUT_DIRECTORY="./output"
+else
+	export OUTPUT_DIRECTORY="$1"
+fi
+
+doxygen Doxyconfig