Use std::mt19937 instead of boost::mt19937

I left the implementation of mt_rng and generate_salt in the campaign_server alone since in the former case,
we might just remove the class, and in the latter I don't build it.

src/generators/cave_map_generator.cpp

@@ -279,7 +279,7 @@ struct passage_path_calculator : pathfind::cost_calculator
 	passage_path_calculator(const t_translation::ter_map& mapdata,
 	                        const t_translation::terrain_code & wall,
 	                        double laziness, size_t windiness,
-							boost::random::mt19937& rng) :
+							std::mt19937& rng) :
 		map_(mapdata), wall_(wall), laziness_(laziness), windiness_(windiness), rng_(rng)
 	{}
 
@@ -289,7 +289,7 @@ struct passage_path_calculator : pathfind::cost_calculator
 	t_translation::terrain_code wall_;
 	double laziness_;
 	size_t windiness_;
-	boost::random::mt19937& rng_;
+	std::mt19937& rng_;
 };
 
 double passage_path_calculator::cost(const map_location& loc, const double) const

src/generators/cave_map_generator.hpp

@@ -86,7 +86,7 @@ class cave_map_generator : public map_generator
 		std::vector<chamber> chambers_;
 		std::vector<passage> passages_;
 		config res_;
-		boost::random::mt19937 rng_;
+		std::mt19937 rng_;
 	};
 
 	bool on_board(const map_location& loc) const

src/generators/default_map_generator_job.hpp

@@ -56,7 +56,7 @@ class default_map_generator_job
 	bool generate_lake(t_translation::ter_map& terrain, int x, int y, int lake_fall_off, std::set<map_location>& locs_touched);
 	map_location random_point_at_side(size_t width, size_t height);
 
-	boost::random::mt19937 rng_;
+	std::mt19937 rng_;
 	const config& game_config_;
 
 };

src/random_new.cpp

@@ -93,7 +93,7 @@ namespace random_new
 	 *  The simplified version I have written should work the same on all
 	 *  platforms, which is the most important thing for us.
 	 *  The existence of "modulo bias" seems less important when we have moved
-	 *  to boost::mt19937, since it guarantees that there are no "bad bits"
+	 *  to std::mt19937, since it guarantees that there are no "bad bits"
 	 *  and has a very large range.
 	 *
 	 *  If a standard cross platform version becomes available then this should

src/scripting/mapgen_lua_kernel.cpp

@@ -43,7 +43,7 @@ struct lua_State;
  */
 static int intf_random(lua_State *L)
 {
-	boost::mt19937& rng = lua_kernel_base::get_lua_kernel<mapgen_lua_kernel>(L).get_default_rng();
+	std::mt19937& rng = lua_kernel_base::get_lua_kernel<mapgen_lua_kernel>(L).get_default_rng();
 	if(lua_isnoneornil(L, 1)) {
 		double r = double (rng());
 		double r_max = double (rng.max());
@@ -201,10 +201,10 @@ uint32_t mapgen_lua_kernel::get_random_seed()
 	}
 }
 
-boost::mt19937& mapgen_lua_kernel::get_default_rng()
+std::mt19937& mapgen_lua_kernel::get_default_rng()
 {
 	if(!default_rng_) {
-		default_rng_ = boost::mt19937(get_random_seed());
+		default_rng_ = std::mt19937(get_random_seed());
 	}
 	return *default_rng_;
 }

src/scripting/mapgen_lua_kernel.hpp

@@ -35,11 +35,11 @@ class mapgen_lua_kernel : public lua_kernel_base {
 	config create_scenario(const char * prog, const config & generator, boost::optional<uint32_t> seed); // throws game::lua_error
 
 	virtual uint32_t get_random_seed();
-	boost::mt19937& get_default_rng();
+	std::mt19937& get_default_rng();
 private:
 	void run_generator(const char * prog, const config & generator);
 	boost::optional<uint32_t> random_seed_;
-	boost::optional<boost::mt19937> default_rng_;
+	boost::optional<std::mt19937> default_rng_;
 };
 
 #endif

src/tests/test_rng.cpp

@@ -28,7 +28,7 @@ BOOST_AUTO_TEST_SUITE( rng )
 */
 BOOST_AUTO_TEST_CASE( validate_mt19937 )
 {
-	boost::mt19937 rng;
+	std::mt19937 rng;
 	for (int i = 0; i < 9999 ; i++) {
 		rng();
 	}