Invert the calling order of `group` and `subgroup` in `load_hk`.

[fincardona]

The first input parameter of the load_hk method is group which is either BIAS or DAQ, while the second is subgroup, that can be either a polarimeter or a board name: https://github.com/lspestrip/striptease/blob/921826363e797db4166a2c7de670c15a4e3eb292/striptease/hdf5files.py#L293 Instead, the first argument of load_sci is the polarimeter name: https://github.com/lspestrip/striptease/blob/921826363e797db4166a2c7de670c15a4e3eb292/striptease/hdf5files.py#L332 It might be useful to invert the calling order of group and subgroup in load_hk to keep it coherent in the two methods.

[planck2007]

This choice has a meaning, strictly connected to the hardware architecture. In the electronics we have BIAS boards and Acquisition boards (DAQ). Each is connected to Polarimeters (either for bias or data acquisition).

For this reason Francesco asked to swap groups and subgroups, to reflect the actual hardware logic.