wine install script to support overrides only.

[Raffarti]

Only overrides supported. #56
Possible developments:

• report former status instead of forcing everything to help diagnostic, maybe add check only option;
• renaming the script (I would keep dlls in the name to avoid it being mistaken for a system wide setup);
• add an option to copy dlls rather than link them.

[doitsujin]

Is there any particular reason you're not simply using an else here instead of that exit; fi construct? This would make the script easier to read in my opinion, although this of course won't stop me from merging the PR.

[Raffarti]

Nothing really, just a stylistic choice. It doesn't feel natural to have the main code in a else statement. This way it's clearer that the reset option is the alt case, and the other is the main purpose of the script.