Added direct force plugin and fixes in stretching energy

Samo Penic

2019-03-09 2c4278db6ead5c27e30a3000097ed898c968534e

 configure.ac

@@ -52,5 +52,7 @@
AC_CHECK_FUNCS([pow sqrt strndup])

AC_CONFIG_FILES([Makefile
                 src/Makefile])
                 src/Makefile
       src/plugins/Makefile
      ])
AC_OUTPUT