inplace_

Matlab versions of the c/c++ operators +=, *= (plus circshift) working in-place and avoiding unneces

To date I implemented a few functions I needed, i.e. some C-like operators and circshift:
inplace(x, y, '+=');
inplace(x, y, '.*=');
inplace(x, ns, 'circshift');
that do not allocate memory and compared to the matlab equivalent
x = x + y;
x = x .* y;
x = circshift(x, ns);
are (when working with arrays above 300-400 MB) much faster (tenths of second instead of a few minutes) because the pc does not start swapping to the disk.
The matlab equivalents are currently optimized (performed in-place) only in M-code, but not at the command line.
See http://blogs.mathworks.com/loren/?p=36 for a discussion about it.
IMPORTANT: this piece of code infringes the recommendation that mex files should not overwrite input data.