M5 field-book observations dropped with code A-J

[zsiki]

In the M5 field-book points observed during freestation are marked with code A/B/C/../J.
These points are stored with Hz before orientation, the following observed points with oriented direction. For a simple solution observations with code A/B/../J are dropped.

A better solution could be to create two stations first with freestation observations and the second with the following observations.