Add support for Kate editor

[jjatria]

This patch adds support for Kate, the default text editor in KDE.

This is a bit different to the existing editors, since unlike the rest, this is a graphical editor (not one that runs in the terminal). Still, when a window is already open, running kate filename will open that file in the existing window, so a utility like ot can be very useful (it certainly has been for me).

The one thing that could be improved is that, if no window is open, ot will create a new one, but will not detach from it, which can be a bit annoying (sadly, Kate does not seem to have an option to avoid this, so it needs to be done with invocations like kate foo &, which I'm not sure if we can use in this case).

Anyway, let me know what you think!

[coveralls]

Pull Request Test Coverage Report for Build 110

• 6 of 6 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.06%) to 98.347%

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Totals
Change from base Build 109:	0.06%
Covered Lines:	119
Relevant Lines:	121

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💛 - Coveralls

[oalders]

@jjatria thanks. This looks great. I was going to ask you to add kate to the docs but after having a look I realized that I haven't clearly documented the already supported editors, so I'll do that before I release this. :)

Not sure what to do about detaching, but let's start with this and see how it goes.

[jjatria]

Thanks for merging this so quickly! 🎉

I agree that thinking about detaching can come later, if at all.

[oalders]

A new version is now on its way to CPAN.