MS_INFO - Information about an elasticity matrix.

Prints out or returns a variety of information about an input elasticity
matrix.

[ ... ] = MS_info( C, ... )

Usage:
    [] = MS_info(C)
        Prints to the screen the default information about the matrix.

[] = MS_info(C, rho)
    If the density is provided, velocity information is returned.

[] = MS_info(C, rho, 'mode', MODE)
    Choose the set of outputs to return. Currently supported are:
      'all' : all available information (default)
      'vel' : just report velocity information
      'rot' : just report rotational information

[] = MS_info(C, 'mode', MODE)
    As above, be default to 'rot'.

[report] = MS_info(C, ...)
    As above, but return information in a string. Don't print to
    screen.