Limit zoom out

We limit the minimum zoom to Z=0.3.  Minimum preset zoom level is 0.31,
so 0.3 is only reachable using the mouse wheel.  Smaller than 0.18, GAL
does not display properly.

Fixes: lp:1773215
* https://bugs.launchpad.net/kicad/+bug/1773215

common/view/view.cpp

@@ -283,7 +283,7 @@ void VIEW::OnDestroy( VIEW_ITEM* aItem )
 VIEW::VIEW( bool aIsDynamic ) :
     m_enableOrderModifier( true ),
     m_scale( 4.0 ),
-    m_minScale( 1.0 ), m_maxScale( 75000.0 ),
+    m_minScale( 4.0 ), m_maxScale( 75000.0 ),
     m_mirrorX( false ), m_mirrorY( false ),
     m_painter( NULL ),
     m_gal( NULL ),