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/azure-pipelines.yml

@@ -0,0 +1,22 @@
+schedules:
+  - cron: "0 0 * * *"
+    displayName: Daily midnight build
+    branches:
+      include:
+      - master
+    always: true
+
+jobs:
+- job: NightlyUpdate
+  pool:
+    vmImage: 'ubuntu-latest'
+  container: perlmint/glew-cmake:20190922
+  steps:
+  - checkout: self
+    persistCredentials: true
+  - bash: |
+      export TEST_MODE=false
+      git config --global user.email $GIT_USEREMAIL &&
+      git config --global user.name $GIT_USERNAME &&
+      unset SYSTEM # remove SYSTEM variable set by azure pipeline
+      ./glew-cmake/maintain.sh