This includes a new class for that and some additions for the config class to handle it. Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@292
(env is not fixed) Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@289
Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@80