Implement mixer /listmidi for coremidi. Thanks for the assistance Dominus

git-svn-id: http://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3838 ed541006-0bf7-43e9-8c4d-6fc63c346d47
CD audio status returns zero start and end times when no track is playing. Fixes The Manhole.

git-svn-id: http://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3839 ed541006-0bf7-43e9-8c4d-6fc63c346d47
Add ADDLOG, which adds a message to the logfile. Convenient when debugging and retracing the resulting log afterwards.

git-svn-id: http://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3840 ed541006-0bf7-43e9-8c4d-6fc63c346d47
make clang happy. Thanks wjp

git-svn-id: http://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3841 ed541006-0bf7-43e9-8c4d-6fc63c346d47
Reenable the setting of the %CONFIG% variable when doing a CONFIG -get command (reported in forum)

git-svn-id: http://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3842 ed541006-0bf7-43e9-8c4d-6fc63c346d47