vapours: add time primitives, fix result name

libraries/libvapours/include/vapours.hpp

@@ -19,6 +19,8 @@
 #include "vapours/defines.hpp"
 #include "vapours/literals.hpp"
 
+#include "vapours/timespan.hpp"
+
 #include "vapours/util.hpp"
 #include "vapours/results.hpp"
 #include "vapours/svc.hpp"