Show channel stats

[cbrnr]

I think it would be useful to add a new option to show channel stats as obtained with raw.describe() (which returns a Pandas dataframe), e.g.:

 0  Fp1   EEG   µV      -321.63     -13.21      -1.94       8.68     712.39
 1  AF7   EEG   µV      -320.12      -9.66      -0.20       9.44     356.74
 2  AF3   EEG   µV      -282.45      -7.04       0.12       7.40     234.54
 3  F1    EEG   µV      -389.73     -21.54      -2.57      16.46     708.45
 4  F3    EEG   µV      -334.93     -13.89      -2.23       9.02     378.99
 5  F5    EEG   µV      -458.99      -7.28      -0.47       6.42     300.37
 6  F7    EEG   µV      -315.50      -7.62      -0.24       7.49     236.63
 7  FT7   EEG   µV     -1200.60      -7.71       0.35       8.36    2662.98
 8  FC5   EEG   µV      -422.04      -6.93       0.32       7.46     232.00
 9  FC3   EEG   µV      -253.39     -11.36      -0.04      11.36     405.27
10  FC1   EEG   µV      -249.88      -6.05       0.46       6.85     117.05
11  C1    EEG   µV      -236.54     -10.62      -0.19      10.44     133.33
12  C3    EEG   µV      -282.18      -5.73       0.22       6.08     122.19
13  C5    EEG   µV      -325.40      -8.38      -0.18       8.09     303.00
14  T7    EEG   µV      -547.49     -25.18      -1.26      23.27     949.80
15  TP7   EEG   µV      -315.58     -15.28      -1.11      13.25     430.67