code refactor

related to #8 (closed):

• I kept changes per commit small, so the number of commits got kind of numerous...

src/icartt/dataset.py

@@ -520,12 +520,8 @@ class Dataset:
         # line 7 - UTC date when data begin, UTC date of data reduction or revision
         # - comma delimited (yyyy, mm, dd, yyyy, mm, dd).
         dmp = f.readline()
-        self.dateOfCollection = datetime.datetime.strptime(
-            "".join(["{:s}".format(x) for x in dmp[:3]]), "%Y%m%d"
-        )
-        self.dateOfRevision = datetime.datetime.strptime(
-            "".join(["{:s}".format(x) for x in dmp[3:6]]), "%Y%m%d"
-        )
+        self.dateOfCollection = datetime.datetime(*map(int, dmp[:3])) # TODO: set UTC ?!
+        self.dateOfRevision = datetime.datetime(*map(int, dmp[3:6]))
 
         # line 8 - Data Interval (This value describes the time spacing (in seconds)
         # between consecutive data records. It is the (constant) interval between