shell32/shlfldr_unixfs: Handle dos sub-paths more robust

[Michael Jung]

I've also replaced some tabs by white spaces in Michael Lin's patch. Hope 
that's ok.

Changelog:
	Replace '\\' by '/' in strings passed to ParseDisplayName to be able to 
handle DOS-style relative paths.

Bye,
-- 
Michael Jung
mjung at iss.tu-darmstadt.de