Fix handling of color for labels

Author: stefan-gaechter-hxgn-geosystems

spatialmath/base/transforms3d.py

@@ -3281,22 +3281,11 @@ def trplot(
         if textcolor == "":
             textcolor = color[0]
 
-        if origincolor != "":
+        if origincolor == "":
             origincolor = color[0]
-        else:
-            origincolor = "black"
 
         # label the frame
         if frame != "":
-            if textcolor is None:
-                textcolor = color[0]
-            else:
-                textcolor = "blue"
-            if origincolor is None:
-                origincolor = color[0]
-            else:
-                origincolor = "black"
-
             o1 = T @ np.array(np.r_[flo, 1])
             ax.text(
                 o1[0],