add wavefront loader

start adding various scenes to test gpu rigid body pipeline
reserve more memory for shapes (concave triangle mesh can be huge) in GLInstancingRenderer
fix a few crashes when 0 objects

demo/ObjLoader/string_extra.cpp

@@ -0,0 +1,16 @@
+#include "string_extra.h"
+#include <string.h>
+
+char strequal(const char *s1, const char *s2)
+{
+	if(strcmp(s1, s2) == 0)
+		return 1;
+	return 0;
+}
+
+char contains(const char *haystack, const char *needle)
+{
+	if(strstr(haystack, needle) == NULL)
+		return 0;
+	return 1;
+}