ECPL spectra

[cdeil]

I just entered an ECPL spectrum:
749958e#diff-501fd4323310af93fb916ffb0b91d117R22

The spectral model parametrisation and parameters are here:
http://www.aanda.org/articles/aa/full/2006/47/aa5546-06/aa5546-06.html

I think the norm might be processed incorrectly, since currently the catalog has:

spec_norm_1TeV: 2.0170070474945234e-11

but the differential flux at 1 TeV should be lower, the difference being the exp factor.

What we need is

• Start by checking this one source
• Check all ECPL spectra in gamma-cat
• Define a better spec result input format, or at least clearly document how the norm is processed for ECPL.

[cdeil]

Actually, @adonath pointed out that this source is correct.

In [4]: np.exp(-1/24.8) * 21.0
Out[4]: 20.170070698235794

To avoid confusion, we'll rename to spec_dnde_1TeV.

I still think we should check the other spectra and define the format more clearly.
Keeping this issue open as a reminder...

[cdeil]

With #119 and #122 the formats are better now.
(we need better docs and validation tools, but the formats are as clear as I could make them)

We're doing review of many spectra by plotting them and comparing to spectral points.
Of course, a systematic review of all ECPL or PL2 spectra would be nice, but I don't think anyone has the time and it's not clear that it's needed.
So closing this issue now.