Usage: <tt>input = [ <i>ax ay az La bx by bz Lb cx cy cz Lc x0 y0 z0 plotonly outside</i> ] 
       removerectbox </tt>

<p>
The regions to be removed are specified in the crystal coordinate system (so coordinate
transformation is involved).  Sorry this one is too complicated to explain.  Please read
the source code (<tt>md.cpp</tt>) or find an example that uses this command.

<p>
This function is useful for creating a prismatic dislocation loop by removing atoms.
