Docstring parsing improvements

[bqpd]

Closes #1198

[mjburton11]

Other is confusing. * Variables

[bqpd]

note to self: make

    """
    Variables
    ---------
    m    [kg ]  Motor mass
    W    [lbf]  Motor weight
    Pmax [W  ]  Max power
    """

throw a meaningful error

[mjburton11]

why does that throw an error?

[bqpd]

spaces in the unit declarations!

[mjburton11]

why is that a bad thing?

[mjburton11]

Ok I tried this for the first time convexengineering/gplibrary@9d78070 and I really like it.

[mjburton11]

I want to get this merged

[mjburton11]

Ok I have a problem on convexengineering/gplibrary@c1b7c9b, the functions in the docstring don't seem to be working. Running wing_test.py

/Users/mjburton11/MIT/GPKIT/library/gpkitmodels/GP/aircraft/wing/wing.py in return_c(self, c)
     44         " return normalized chord distribution "
     45         return np.array([2./(1+c[self.lam])*(1+(c[self.lam]-1)*e) for e
---> 46                          in c[self.eta]])
     47 
     48     def return_cmac(self, c):

AttributeError: 'Planform' object has no attribute 'eta'

[bqpd]

@mjburton11 the problem was the spaces in np.linspace(0,1,5) in the declaration of eta

[bqpd]

I used a print parse_variables(Planform.__doc__) line to debug

[bqpd]

test models please

[bqpd]

@mjburton11 it's now on master