Add gps_alt, gps_lon, gps_lat to the variables filtered by persistence QC

[BaptisteVandecrux]

Issue spotted at numerous sites. Example here at TAS_A:

GEUS-Glaciology-and-Climate/PROMICE-AWS-data-issues#114

[BaptisteVandecrux]

Of course there are complications with the use of persistence QC.

At several sites, lat/lon/elevation have degraded precision, which, depending on the magnitude and direction of their movement, lead to long periods of constant longitude or latitude that are not a malfunction, but many good measurement rounded and saved with identical digits.

If we use persistence QC in those situation, we will throw out true measurements.
See an example below with NUK_L: