Several fixes

A container branch for the fixes of several issues I encountered while rolling out the current SaQC on the SEEFO pipeline.

Not sure, if this needs a real review, but as some of the changes touched code I am not completely familiar with, maybe you, @palmb and @luenensc want to have a look anyhow?

saqc/core/register.py

@@ -210,13 +210,6 @@ def _getMaskingThresh(masking, kwargs, fname):
     if not isinstance(thresh, (bool, float, int)):
         raise TypeError(f"'to_mask' must be of type bool or float")
 
-    if masking == "none" and thresh not in (False, np.inf):
-        # TODO: fix warning reference to docu
-        warnings.warn(
-            f"the saqc-function {fname!r} ignores masking and therefore does not evaluate the passed "
-            f"'to_mask'-keyword. Please refer to the documentation: TODO"
-        )
-
     if thresh is True:  # masking ON
         thresh = UNFLAGGED