Correct launch-game.cmd join of quoted paths

[jbfil]

Unquote strings in launch-game.cmd and quote on use. Now correctly finds directory when there are quotes in the mod.config files.

fixes #175

[jbfil]

The default make all invocation seems to create only the 'engine' directory and not a release tagged version as expected here. Not sure that it would be correct to change this as well.

git diff mod.config
diff --git a/mod.config b/mod.config
index 7c0ab03..f5a0aab 100644
--- a/mod.config
+++ b/mod.config
@@ -9,7 +9,7 @@
 MOD_ID="example"

 # The OpenRA engine version to use for this project.
-ENGINE_VERSION="release-20230225"
+ENGINE_VERSION="engine"

 ##############################################################################
 # Packaging

[abcdefg30]

It does create it and write the string into the VERSION file for me.