Another attempt to fix the select-reference-point toolstack thing.

This time remove the push/pop from the picker tools as that's
responsible for the issue of trying to re-activate the move action
when its popped.  Instead do the push/pop from the client code
of other actions that need it, and not at all from the move-with-
reference action.

Fixes https://gitlab.com/kicad/code/kicad/issues/5336

common/tool/tools_holder.cpp

@@ -96,13 +96,6 @@ void TOOLS_HOLDER::PopTool( const std::string& actionName )
 }
 
 
-void TOOLS_HOLDER::ClearToolStack()
-{
-    m_toolStack.clear();
-    DisplayToolMsg( ACTIONS::selectionTool.GetLabel() );
-}
-
-
 std::string TOOLS_HOLDER::CurrentToolName() const
 {
     if( m_toolStack.empty() )