Missing f107 in source data for 2011-01-01

[petermao]

The 2011 file at ftp://ftp.ngdc.noaa.gov/STP/GEOMAGNETIC_DATA/INDICES/KP_AP/ is missing the f107 value for the first day of the year. In get_indices, this gets loaded as NaN, which wreaks havoc on codes that use this package such as MSIS-E00.

I "solved" the problem locally, by editing the 2011 file directly:

1101012421 213 7 0 71013 720 77  5  3  0  3  4  5  3  7  40.10 37088.03
                                                                 ^^^^^

My inclination is to make this code or those that depend on it more robust against NaNs, but that may not be welcomed by all users.