add package.xml to support colcon builds

Author: cmnrd

package.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0"?>
+<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="3">
+ <name>reactor-cpp</name>
+ <version>0.0.0</version>
+ <description>A C++ reactor runtime</description>
+ <maintainer email="[email protected]">user</maintainer>
+ <license>ISC License</license>
+ <export>
+   <build_type>cmake</build_type>
+ </export>
+</package>
+<package format="3">
+ <name>reactor-cpp-foo</name>
+ <version>0.0.0</version>
+ <description>A C++ reactor runtime</description>
+ <maintainer email="[email protected]">user</maintainer>
+ <license>ISC License</license>
+ <export>
+   <build_type>cmake</build_type>
+ </export>
+</package>