cosmetics
Reduce variable scope.
remove unneeded variable
Enable C4701 for /W3.
MainFrm.cpp: remove unused variables.
VobSubFile.cpp: break after return doesn't make sense.
Fix using potentially uninitialized local variable.
DX9RenderingEngine.cpp: Fix leaking memory due to an exception.
Remove unneeded typedef.
Remove extra arguments from format strings.

(/analyze warning C6271)
Avoid variable shadowing.
DVBSub: Add an assert.
Don't pass structures to printf-like functions.
Cosmetics: Rename some variables to make clear they are member variables.
Ensure that the release order of the DS interfaces is consistent.