Add support for user-defined control codes

[vsrs]

Minor addition, no breaking changes.

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This change is 

[dlon]

Reviewed 4 of 4 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @vsrs)

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src/service.rs line 82 at r1 (raw file):

        /// Can use user-defined control codes
        const NOTIFY = Services::SERVICE_USER_DEFINED_CONTROL;

Should we perhaps be consistent with the naming here? I.e., USER_DEFINED_CONTROL in this case.

[vsrs]

Reviewable status: 2 of 4 files reviewed, 1 unresolved discussion (waiting on @dlon)

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src/service.rs line 82 at r1 (raw file):

Previously, dlon (David Lönnhager) wrote…

Should we stick to naming these the same as the Windows constants? I.e., USER_DEFINED_CONTROL in this case.

That makes sense, thank you. I've updated the code.

[vsrs]

@dlon, may you please complete the review? Thanks.

[dlon]

Reviewed 2 of 2 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

[dlon]

Thanks!