Modernize source code: last part (#6285)

* Modernize source code: last par

* Use empty when needed
* Use emplace_back instead of push_back when needed
* For range-based loops
* Initializers fixes
* constructors, destructors default
* c++ C stl includes

src/script/lua_api/l_client.cpp

@@ -34,7 +34,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "util/string.h"
 #include "nodedef.h"
 
-
 int ModApiClient::l_get_current_modname(lua_State *L)
 {
 	lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);