start.exe: Implement /D option, add new wine specific feature allowing to specify the shell operation name

[Paul Chitescu]

Changelog: start.exe: Implement /D option, add new wine specific feature 
allowing to specify the shell operation name.

The new /O[peration] command line option allows to specify a shell operation 
other than "open". This is very valuable for testing or implementing actions 
from shell scripts.

It is also possible to pass a NULL operation by specifying the empty string 
'' (or whatever looks like in your preferred shell).

Examples:
wine start /d 'c:\' notepad.exe
wine start /o print README.txt