add support for selecting from various penalty matrices

[dswah]

create a few standard penalty matrices to chose from:

• 2nd order smoothing (TOP)
• circular smoothing (periodic data) (TOP)
• harmonic smoothing (i think this is just p>=1) (TOP)
• monotone smoothing (TOP)
• non-negative impulse response
• varying penalties
• etc

[dswah]

monotone smoothing and convex smoothing doent make too much sense as penalties since why you want to slightly enforce them?

ive moved them to constraints.

right now we've got

PENALTIES = {'auto': 'auto',
             'derivative': derivative,
             'l2': l2,
             'none': none,
            }

CONSTRAINTS = {'convex': convex,
               'concave': concave,
               'monotonic_inc': monotonic_inc,
               'monotonic_dec': monotonic_dec,
               'circular': circular,
               'none': none
              }

where derivative means 2order smoothing

[dswah]

just change the name of derivative to something more intuitive (and maybe make it more interactive ie choose difference order?).

this is done.