[Python] Make StartVector public

Make StartVector vector public since it is already being used in
generated code

Author: satur9nine

python/flatbuffers/builder.py

@@ -422,7 +422,6 @@ def PrependUOffsetTRelative(self, off):
     off2 = self.Offset() - off + N.UOffsetTFlags.bytewidth
     self.PlaceUOffsetT(off2)
 
-  ## @cond FLATBUFFERS_INTERNAL
   def StartVector(self, elemSize, numElems, alignment):
     """StartVector initializes bookkeeping for writing a new vector.
 
@@ -438,8 +437,6 @@ def StartVector(self, elemSize, numElems, alignment):
     self.Prep(alignment, elemSize * numElems)  # In case alignment > int.
     return self.Offset()
 
-  ## @endcond
-
   def EndVector(self, numElems=None):
     """EndVector writes data necessary to finish vector construction."""