[ODE] Fixed Joint

[Frederik Schneider]

Hello together,

I'm searching for the best way to clue some bodies together.
The tricky thing is, that they need to be breakable.
For exampla like a wall of bricks and cement.

I thought the fixed joint would be good, but the manual discourages the 
use of it.
What is the exact reason for that, is it unstable?

If I need to use an other joint type and constrain it in all directions, 
which one would be the best choice (performance, stabillity):

thanks in advance

Frederik