feat(gx): add incomplete 'CGxDeviceGLSDL' (#2)

* chore(build): add vendored SDL 3.0.0 library

* chore(build): add vendored glew-cmake-2.2.0 library

* feat(console): in the presence of -opengl launch flag, change GxApi to OpenGl

* feat(gx): add uncompleted CGxDeviceGLSDL targeting Windows and Linux

* chore(build): change SDL3 linkage from shared (bad) to to static (good)

vendor/glew-cmake-2.2.0/auto/bin/update_ext.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+##
+## Copyright (C) 2008-2019, Nigel Stewart <nigels[]users sourceforge net>
+## Copyright (C) 2002-2008, Marcelo E. Magallon <mmagallo[]debian org>
+## Copyright (C) 2002-2008, Milan Ikits <milan ikits[]ieee org>
+##
+## This program is distributed under the terms and conditions of the GNU
+## General Public License Version 2 as published by the Free Software
+## Foundation or, at your option, any later version.
+##
+## Parameters:
+##
+##       $1: Extensions directory
+##       $2: Registry directory
+##       $3: The black list
+
+set -e
+
+if [ ! -d $1 ] ; then
+    mkdir -p $1
+
+# Parse each of the extensions in the registry
+    find $2 -name doc -type d -prune -o -name "*.txt" -print | \
+	grep -v -f $3 | sort | bin/parse_spec.pl $1
+
+fi