Single unit instances work with whiteboard.

Here the changes to get whiteboard to work are mostly cosmetic, the
right cost for each unit is displayed on the unit in question.  This
is mostly for peace of mind as the user looks at the screen they don't
get confused.  The proper gold is also taken for each recall and
replaced for each canceled/undone recall while in whiteboard.

src/whiteboard/recall.cpp

@@ -116,6 +116,9 @@ void recall::execute(bool& success, bool& complete)
 	temporary_unit_hider const raii(*fake_unit_);
 	//Give back the spent gold so we don't get "not enough gold" message
 	int cost = current_team.recall_cost();
+	if (temp_unit_->recall_cost() > -1) {
+		cost=temp_unit_->recall_cost();
+	}
 	current_team.get_side_actions()->change_gold_spent_by(-cost);
 	bool const result = actions::recall_unit(temp_unit_->id(), current_team, recall_hex_, map_location::null_location);
 	if (!result) {
@@ -137,15 +140,18 @@ void recall::apply_temp_modifier(unit_map& unit_map)
 	std::vector<unit>::iterator it = find_if_matches_id(recalls, temp_unit_->id());
 	assert(it != recalls.end());
 	recalls.erase(it);
-
+	
 	// Temporarily insert unit into unit_map
 	//unit map takes ownership of temp_unit
 	unit_map.insert(temp_unit_.release());
 
 	//Add cost to money spent on recruits.
 	int cost = resources::teams->at(team_index()).recall_cost();
-	resources::teams->at(team_index()).get_side_actions()->change_gold_spent_by(cost);
+	if (it->recall_cost() > -1) {
+		cost = it->recall_cost();
+	}
 
+	resources::teams->at(team_index()).get_side_actions()->change_gold_spent_by(cost);
 	// Update gold in top bar
 	resources::screen->invalidate_game_status();
 }
@@ -167,7 +173,15 @@ void recall::draw_hex(map_location const& hex)
 		const double y_offset = 0.7;
 		//position 0,0 in the hex is the upper left corner
 		std::stringstream number_text;
-		number_text << utils::unicode_minus << resources::teams->at(team_index()).recall_cost();
+//		number_text << utils::unicode_minus << resources::teams->at(team_index()).recall_cost();
+		unit &it = *get_unit();
+		int cost = statistics::un_recall_unit_cost(it);
+		if (cost < 0) {
+			number_text << utils::unicode_minus << resources::teams->at(team_index()).recall_cost();
+		}
+		else {
+			number_text << utils::unicode_minus << cost;
+		}
 		size_t font_size = 16;
 		SDL_Color color; color.r = 255; color.g = 0; color.b = 0; //red
 		resources::screen->draw_text_in_hex(hex, display::LAYER_ACTIONS_NUMBERING,