Add command flag to disable shift-key estimate mode in DoCommandP

src/command.cpp

@@ -881,6 +881,7 @@ bool DoCommandPEx(TileIndex tile, uint32 p1, uint32 p2, uint64 p3, uint32 cmd, C
 	bool estimate_only = _shift_pressed && IsLocalCompany() &&
 			!_generating_world &&
 			!(cmd & CMD_NETWORK_COMMAND) &&
+			!(cmd & CMD_NO_SHIFT_ESTIMATE) &&
 			!(GetCommandFlags(cmd) & CMD_NO_EST);
 
 	/* We're only sending the command, so don't do

src/command_type.h

@@ -510,6 +510,7 @@ DECLARE_ENUM_AS_BIT_SET(DoCommandFlag)
  */
 enum FlaggedCommands {
 	CMD_NETWORK_COMMAND       = 0x0100, ///< execute the command without sending it on the network
+	CMD_NO_SHIFT_ESTIMATE     = 0x0200, ///< do not check shift key state for whether to estimate command
 	CMD_FLAGS_MASK            = 0xFF00, ///< mask for all command flags
 	CMD_ID_MASK               = 0x00FF, ///< mask for the command ID
 };