housekeeping - JC will need to fix this

moved visual studio project to its own build directory, added to
gitignore so we're not versioning the build products. i don't do
windows, so Jinduan will have to make sure everything still works with
this directory structure.

.gitignore

@@ -118,6 +118,6 @@ xcuserdata
 *.bi
 *.opensdf
 test/*
-
+Debug/