OpenSCAD: [skip ci] set default of 16 for useMaxFN parameter

src/Mod/OpenSCAD/Resources/ui/openscadprefs-base.ui

@@ -153,7 +153,7 @@
            <string>The maximum number of faces of a polygon, prism or frustum. If fn is greater than this value the object is considered to be a circular. Set to 0 for no limit</string>
           </property>
           <property name="value">
-           <number>0</number>
+           <number>16</number>
           </property>
           <property name="prefEntry" stdset="0">
            <cstring>useMaxFN</cstring>

src/Mod/OpenSCAD/importCSG.py

@@ -925,7 +925,7 @@ def p_cylinder_action(p):
     n = int(round(float(p[3]['$fn'])))
     fnmax = FreeCAD.ParamGet(\
         "User parameter:BaseApp/Preferences/Mod/OpenSCAD").\
-        GetInt('useMaxFN')
+        GetInt('useMaxFN', 16)
     if printverbose: print(p[3])
     if h > 0:
         if ( r1 == r2 and r1 > 0):