MSVC build issues

[Mahno9]

Trying to build raylib-cpp with MSVC I've got two issues:

1. Incorrect linker flags for MSVC (cl.exe) specified in tests\CMakeLists.txt. Seems like there are flags only for gcc and no option for MSVC.

[build] cl : command line error D8021: invalid numeric argument '/Wextra' [C:\Projects\C++\raylib-cpp\build_vscode\tests\raylib_test.vcxproj]

2. The next error appear in case of type conversion from initializer list to Vector3:
   (Godbolt link with the error reproducing)

[build] C:\Projects\C++\raylib-cpp\examples\core\core_world_screen.cpp(46,110): error C4576: a parenthesized type followed by an initializer list is a non-standard explicit type conversion syntax [C:\Projects\C++\raylib-cpp\build_vscode\examples\core_world_screen.vcxproj

[Mahno9]

MR with proposed fixes: #140

[RobLoach]

This is great. Thanks a lot for pushing this forwards.