Allow btBulletWorldImporter to convert/export a .bullet file to XML

Add first version of btBulletXmlWorldImporter, still incomplete but it can read some files
Fix false assert in btSequentialImpulseConstraintSolver

Extras/Serialize/BulletFileLoader/bDNA.cpp

@@ -347,7 +347,6 @@ static int name_is_array(char* name, int* dim1, int* dim2) {
 // ----------------------------------------------------- //
 void bDNA::init(char *data, int len, bool swap)
 {
-	printf("swap = %d\n",swap);
 	int *intPtr=0;short *shtPtr=0;
 	char *cp = 0;int dataLen =0;long nr=0;
 	intPtr = (int*)data;