Add test compile warning flag effc++ and fix findings

Author: und3f

include/Gamepad.hpp

@@ -12,7 +12,7 @@ namespace raylib {
  */
 class Gamepad {
 public:
-    Gamepad(int gamepadNumber = 0) { set(gamepadNumber); }
+    Gamepad(int gamepadNumber = 0) : number(gamepadNumber) {};
     int number;
 
     GETTERSETTER(int, Number, number)

tests/CMakeLists.txt

@@ -8,7 +8,7 @@ add_executable(raylib_cpp_test raylib_cpp_test.cpp)
 if (MSVC)
     target_compile_options(raylib_cpp_test PRIVATE /Wall /W4)
 else()
-    target_compile_options(raylib_cpp_test PRIVATE -Wall -Wextra -Wconversion -Wsign-conversion)
+    target_compile_options(raylib_cpp_test PRIVATE -Wall -Wextra -Wconversion -Wsign-conversion -Weffc++)
 endif()
 target_link_libraries(raylib_cpp_test raylib_cpp raylib)