Support 3 drag vs. select options, and unifiy with other drag prefs.

Fixes https://gitlab.com/kicad/code/kicad/issues/5493

common/tool/tools_holder.cpp

@@ -35,7 +35,7 @@ TOOLS_HOLDER::TOOLS_HOLDER() :
         m_actions( nullptr ),
         m_toolDispatcher( nullptr ),
         m_immediateActions( true ),
-        m_dragSelects( true ),
+        m_dragAction( KIGFX::MOUSE_DRAG_ACTION::SELECT ),
         m_moveWarpsCursor( true )
 { }
 
@@ -122,7 +122,7 @@ void TOOLS_HOLDER::CommonSettingsChanged( bool aEnvVarsChanged, bool aTextVarsCh
     COMMON_SETTINGS* settings = Pgm().GetCommonSettings();
 
     m_moveWarpsCursor = settings->m_Input.warp_mouse_on_move;
-    m_dragSelects = settings->m_Input.prefer_select_to_drag;
+    m_dragAction = static_cast<KIGFX::MOUSE_DRAG_ACTION>( settings->m_Input.drag_left );
     m_immediateActions = settings->m_Input.immediate_actions;
 }