Added GIMPACT integration for moving concave meshes (interaction with all other Bullet collision shapes)

Thanks a lot to Francisco León Nájera for the contribution!

Extras/GIMPACT/src/gim_math.cpp

@@ -0,0 +1,62 @@
+/*
+-----------------------------------------------------------------------------
+This source file is part of GIMPACT Library.
+
+For the latest info, see http://gimpact.sourceforge.net/
+
+Copyright (c) 2006 Francisco Leon Najera. C.C. 80087371.
+email: projectileman@yahoo.com
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of EITHER:
+   (1) The GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 2.1 of the License, or (at
+       your option) any later version. The text of the GNU Lesser
+       General Public License is included with this library in the
+       file GIMPACT-LICENSE-LGPL.TXT.
+   (2) The BSD-style license that is included with this library in
+       the file GIMPACT-LICENSE-BSD.TXT.
+   (3) The zlib/libpng license that is included with this library in
+       the file GIMPACT-LICENSE-ZLIB.TXT.
+
+ This library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files
+ GIMPACT-LICENSE-LGPL.TXT, GIMPACT-LICENSE-ZLIB.TXT and GIMPACT-LICENSE-BSD.TXT for more details.
+
+-----------------------------------------------------------------------------
+*/
+
+
+#include "GIMPACT/gim_math.h"
+#include "stdlib.h"
+#include "time.h"
+
+
+GREAL gim_inv_sqrt(GREAL f)
+{
+    GREAL r;
+    GIM_INV_SQRT(f,r);
+    return r;
+}
+
+GREAL gim_sqrt(GREAL f)
+{
+    GREAL r;
+    GIM_SQRT(f,r);
+    return r;
+}
+
+//!Initializes mathematical functions
+void gim_init_math()
+{
+    srand(time(0));
+}
+
+//! Generates an unit random
+GREAL gim_unit_random()
+{
+    GREAL rn = rand();
+    rn/=(GREAL)RAND_MAX;
+    return rn;
+}