Added update script and fixed scons on osx

SConstruct

@@ -51,9 +51,11 @@ if env['platform'] == "osx":
     cpp_library += '.osx'
     if env['target'] in ('debug', 'd'):
         env.Append(CCFLAGS=['-g', '-O2', '-arch', 'x86_64'])
+        env.Append(CXXFLAGS=['-std=c++17'])
         env.Append(LINKFLAGS=['-arch', 'x86_64'])
     else:
         env.Append(CCFLAGS=['-g', '-O3', '-arch', 'x86_64'])
+        env.Append(CXXFLAGS=['-std=c++17'])
         env.Append(LINKFLAGS=['-arch', 'x86_64'])
 
 elif env['platform'] in ('x11', 'linux'):

update.sh

+#!/bin/bash
+git submodule update --init --recursive
+cd src/godot-cpp
+scons platform=$1 generate_bindings=yes
+cd ../..
+scons platform=$1