cartiso: bug fixes and math improvements
cartiso: bug fixes and math improvements

cartiso.c:
    Updated usage re amplitude
    Better isothresh selection for sin/isosurf topology
    Amplitude selection independent of isothresh
    Fixed centertask computations
    Fixed Gaussian function scaling factor
    Reduced redundancy in sinusoid scaling

PETTT/miniIO,PETTT/miniIO,PETTT/miniIO,PETTT/miniIO