Update Colvars library to version 2016-12-22

Significant code cleanup and several fixes (walls + extended Lagrangian)

New harmonicWalls bias to apply confining boundaries with time-dependent force
constant & integration

lib/colvars/colvarscript.cpp

@@ -1,5 +1,12 @@
 // -*- c++ -*-
 
+// This file is part of the Collective Variables module (Colvars).
+// The original version of Colvars and its updates are located at:
+// https://github.com/colvars/colvars
+// Please update all Colvars source files before making any changes.
+// If you wish to distribute your changes, please submit them to the
+// Colvars repository at GitHub.
+
 #include <cstdlib>
 #include <stdlib.h>
 #include <string.h>