Fix a non-existing bitmap issue.

the bitmap BITMAPS::calculator, although in bitmaps_list.h, does not exists.
A suitable bitmap can be BITMAPS::icon_pcbcalculator_24.
So it is now used in ACTIONS::showCalculatorTool()

common/tool/actions.cpp

@@ -1248,7 +1248,7 @@ TOOL_ACTION ACTIONS::showCalculatorTools( TOOL_ACTION_ARGS()
         .Scope( AS_GLOBAL )
         .FriendlyName( _( "Calculator Tools" ) )
         .Tooltip( _( "Run component calculations, track width calculations, etc." ) )
-        .Icon( BITMAPS::calculator )
+        .Icon( BITMAPS::icon_pcbcalculator_24 )
         .Flags( AF_NONE )
         .Parameter( FRAME_CALC ) );
 

include/bitmaps/bitmaps_list.h

@@ -114,7 +114,6 @@ enum class BITMAPS : unsigned int
     bug,
     bus_definition_tool,
     c_microstrip,
-    calculator,
     cancel,
     chamfer,
     change_entry_orient,