Improve ModelChainResult.__repr__

[wholmgren]

did not require in #1076... we should improve the ModelChainResult.__repr__. See details below for what it currently looks like. A simple improvement might be a new line between the attribute and data, then a blank line between the end of the data and the next attribute name. Perhaps some indentation would help keep track of results from multiple arrays.

ModelChainResult(solar_position=                           apparent_zenith      zenith  apparent_elevation  \
2020-12-01 00:00:00-07:00       169.300758  169.300758          -79.300758   
2020-12-01 00:05:00-07:00       169.539192  169.539192          -79.539192   
2020-12-01 00:10:00-07:00       169.663237  169.663237          -79.663237   
2020-12-01 00:15:00-07:00       169.668762  169.668762          -79.668762   
2020-12-01 00:20:00-07:00       169.555581  169.555581          -79.555581   
...                                    ...         ...                 ...   
2020-12-02 23:40:00-07:00       167.518383  167.518383          -77.518383   
2020-12-02 23:45:00-07:00       168.144707  168.144707          -78.144707   
2020-12-02 23:50:00-07:00       168.696851  168.696851          -78.696851   
2020-12-02 23:55:00-07:00       169.163414  169.163414          -79.163414   
2020-12-03 00:00:00-07:00       169.532897  169.532897          -79.532897   

                           elevation     azimuth  equation_of_time  
2020-12-01 00:00:00-07:00 -79.300758  343.920897         10.897119  
2020-12-01 00:05:00-07:00 -79.539192  350.104880         10.895814  
2020-12-01 00:10:00-07:00 -79.663237  356.495783         10.894508  
2020-12-01 00:15:00-07:00 -79.668762    2.963292         10.893202  
2020-12-01 00:20:00-07:00 -79.555581    9.367007         10.891897  
...                              ...         ...               ...  
2020-12-02 23:40:00-07:00 -77.518383  321.421138         10.129835  
2020-12-02 23:45:00-07:00 -78.144707  326.040347         10.128458  
2020-12-02 23:50:00-07:00 -78.696851  331.110143         10.127082  
2020-12-02 23:55:00-07:00 -79.163414  336.628915         10.125705  
2020-12-03 00:00:00-07:00 -79.532897  342.565345         10.124328  

[577 rows x 6 columns], airmass=                           airmass_relative  airmass_absolute
2020-12-01 00:00:00-07:00               NaN               NaN
2020-12-01 00:05:00-07:00               NaN               NaN
2020-12-01 00:10:00-07:00               NaN               NaN
2020-12-01 00:15:00-07:00               NaN               NaN
2020-12-01 00:20:00-07:00               NaN               NaN
...                                     ...               ...
2020-12-02 23:40:00-07:00               NaN               NaN
2020-12-02 23:45:00-07:00               NaN               NaN
2020-12-02 23:50:00-07:00               NaN               NaN
2020-12-02 23:55:00-07:00               NaN               NaN
2020-12-03 00:00:00-07:00               NaN               NaN

[577 rows x 2 columns], ac=2020-12-01 00:00:00-07:00    0.0
2020-12-01 00:05:00-07:00    0.0
2020-12-01 00:10:00-07:00    0.0
2020-12-01 00:15:00-07:00    0.0
2020-12-01 00:20:00-07:00    0.0
                            ... 
2020-12-02 23:40:00-07:00    0.0
2020-12-02 23:45:00-07:00    0.0
2020-12-02 23:50:00-07:00    0.0
2020-12-02 23:55:00-07:00    0.0
2020-12-03 00:00:00-07:00    0.0
Freq: 5T, Length: 577, dtype: float64, total_irrad=                           poa_global  poa_direct  poa_diffuse  \
2020-12-01 00:00:00-07:00         0.0        -0.0          0.0   
2020-12-01 00:05:00-07:00         0.0        -0.0          0.0   
2020-12-01 00:10:00-07:00         0.0        -0.0          0.0   
2020-12-01 00:15:00-07:00         0.0        -0.0          0.0   
2020-12-01 00:20:00-07:00         0.0        -0.0          0.0   
...                               ...         ...          ...   
2020-12-02 23:40:00-07:00         0.0        -0.0          0.0   
2020-12-02 23:45:00-07:00         0.0        -0.0          0.0   
2020-12-02 23:50:00-07:00         0.0        -0.0          0.0   
2020-12-02 23:55:00-07:00         0.0        -0.0          0.0   
2020-12-03 00:00:00-07:00         0.0        -0.0          0.0   

                           poa_sky_diffuse  poa_ground_diffuse  
2020-12-01 00:00:00-07:00              0.0                 0.0  
2020-12-01 00:05:00-07:00              0.0                 0.0  
2020-12-01 00:10:00-07:00              0.0                 0.0  
2020-12-01 00:15:00-07:00              0.0                 0.0  
2020-12-01 00:20:00-07:00              0.0                 0.0  
...                                    ...                 ...  
2020-12-02 23:40:00-07:00              0.0                 0.0  
2020-12-02 23:45:00-07:00              0.0                 0.0  
2020-12-02 23:50:00-07:00              0.0                 0.0  
2020-12-02 23:55:00-07:00              0.0                 0.0  
2020-12-03 00:00:00-07:00              0.0                 0.0  

[577 rows x 5 columns], aoi=2020-12-01 00:00:00-07:00    169.300758
2020-12-01 00:05:00-07:00    169.539192
2020-12-01 00:10:00-07:00    169.663237
2020-12-01 00:15:00-07:00    169.668762
2020-12-01 00:20:00-07:00    169.555581
                                ...    
2020-12-02 23:40:00-07:00    167.518383
2020-12-02 23:45:00-07:00    168.144707
2020-12-02 23:50:00-07:00    168.696851
2020-12-02 23:55:00-07:00    169.163414
2020-12-03 00:00:00-07:00    169.532897
Freq: 5T, Name: aoi, Length: 577, dtype: float64, aoi_modifier=2020-12-01 00:00:00-07:00    0.0
2020-12-01 00:05:00-07:00    0.0
2020-12-01 00:10:00-07:00    0.0
2020-12-01 00:15:00-07:00    0.0
2020-12-01 00:20:00-07:00    0.0
                            ... 
2020-12-02 23:40:00-07:00    0.0
2020-12-02 23:45:00-07:00    0.0
2020-12-02 23:50:00-07:00    0.0
2020-12-02 23:55:00-07:00    0.0
2020-12-03 00:00:00-07:00    0.0
Freq: 5T, Length: 577, dtype: float64, spectral_modifier=1, cell_temperature=2020-12-01 00:00:00-07:00    20.0
2020-12-01 00:05:00-07:00    20.0
2020-12-01 00:10:00-07:00    20.0
2020-12-01 00:15:00-07:00    20.0
2020-12-01 00:20:00-07:00    20.0
                             ... 
2020-12-02 23:40:00-07:00    20.0
2020-12-02 23:45:00-07:00    20.0
2020-12-02 23:50:00-07:00    20.0
2020-12-02 23:55:00-07:00    20.0
2020-12-03 00:00:00-07:00    20.0
Freq: 5T, Length: 577, dtype: float64, effective_irradiance=2020-12-01 00:00:00-07:00    0.0
2020-12-01 00:05:00-07:00    0.0
2020-12-01 00:10:00-07:00    0.0
2020-12-01 00:15:00-07:00    0.0
2020-12-01 00:20:00-07:00    0.0
                            ... 
2020-12-02 23:40:00-07:00    0.0
2020-12-02 23:45:00-07:00    0.0
2020-12-02 23:50:00-07:00    0.0
2020-12-02 23:55:00-07:00    0.0
2020-12-03 00:00:00-07:00    0.0
Freq: 5T, Length: 577, dtype: float64, dc=2020-12-01 00:00:00-07:00    0.0
2020-12-01 00:05:00-07:00    0.0
2020-12-01 00:10:00-07:00    0.0
2020-12-01 00:15:00-07:00    0.0
2020-12-01 00:20:00-07:00    0.0
                            ... 
2020-12-02 23:40:00-07:00    0.0
2020-12-02 23:45:00-07:00    0.0
2020-12-02 23:50:00-07:00    0.0
2020-12-02 23:55:00-07:00    0.0
2020-12-03 00:00:00-07:00    0.0
Freq: 5T, Length: 577, dtype: float64, array_ac=None, diode_params=None)

Originally posted by @wholmgren in #1076 (comment)