Merge branch 'master' into jgrpp

# Conflicts:
#	regression/regression/result.txt
#	src/aircraft_cmd.cpp
#	src/airport_gui.cpp
#	src/articulated_vehicles.cpp
#	src/console_cmds.cpp
#	src/date_gui.cpp
#	src/engine.cpp
#	src/genworld_gui.cpp
#	src/gfx_layout_fallback.cpp
#	src/group_gui.cpp
#	src/hotkeys.cpp
#	src/network/core/tcp_connect.cpp
#	src/network/core/tcp_listen.h
#	src/newgrf.cpp
#	src/newgrf.h
#	src/newgrf_engine.cpp
#	src/newgrf_gui.cpp
#	src/newgrf_station.cpp
#	src/openttd.cpp
#	src/order_gui.cpp
#	src/os/macosx/osx_main.cpp
#	src/pathfinder/yapf/yapf_node_rail.hpp
#	src/rail_gui.cpp
#	src/saveload/afterload.cpp
#	src/saveload/cargopacket_sl.cpp
#	src/saveload/linkgraph_sl.cpp
#	src/saveload/station_sl.cpp
#	src/script/api/script_industrytype.cpp
#	src/settings.cpp
#	src/settings_gui.cpp
#	src/settings_table.cpp
#	src/settingsgen/settingsgen.cpp
#	src/station.cpp
#	src/station_cmd.cpp
#	src/strings.cpp
#	src/timer/timer_game_calendar.cpp
#	src/timer/timer_game_calendar.h
#	src/timer/timer_manager.h
#	src/timer/timer_window.cpp
#	src/timetable_cmd.cpp
#	src/toolbar_gui.cpp
#	src/town_cmd.cpp
#	src/town_gui.cpp
#	src/train_gui.cpp
#	src/vehicle_cmd.h
#	src/vehicle_gui.cpp
#	src/viewport.cpp
#	src/widgets/dropdown.cpp
#	src/window_func.h
#	src/window_gui.h

src/core/kdtree.hpp

@@ -55,7 +55,7 @@ class Kdtree {
 	/** Create one new node in the tree, return its index in the pool */
 	size_t AddNode(const T &element)
 	{
-		if (this->free_list.size() == 0) {
+		if (this->free_list.empty()) {
 			this->nodes.emplace_back(element);
 			return this->nodes.size() - 1;
 		} else {

src/core/pool_func.cpp

@@ -20,7 +20,7 @@
 {
 	PoolVector *pools = PoolBase::GetPools();
 	pools->erase(std::find(pools->begin(), pools->end(), this));
-	if (pools->size() == 0) delete pools;
+	if (pools->empty()) delete pools;
 }
 
 /**

src/core/span_type.hpp

@@ -85,7 +85,7 @@ public:
 	constexpr pointer data() const noexcept { return first; }
 	constexpr size_t size() const noexcept { return static_cast<size_t>( last - first ); }
 	constexpr std::ptrdiff_t ssize() const noexcept { return static_cast<std::ptrdiff_t>( last - first ); }
-	constexpr bool empty() const noexcept { return size() == 0; }
+	constexpr bool empty() const noexcept { return this->size() == 0; }
 
 	constexpr iterator begin() const noexcept { return iterator(first); }
 	constexpr iterator end() const noexcept { return iterator(last); }