Create mempool.space plugin, improve 2 other plugins.

[jonathanalevi]

The main thing I wanted to propose was a new mempool.space plugin that I created.

I don't know how to use GitHub, so I don't know how to do a PR without also submitting other small changes I made, including updating the Transferwise plugin and changing the ₿ symbol in the Bitfinex plugin. Feel free to omit those, I just don't know how.

Add my mempool plugin, it's awesome, I think you'll like it a lot.

[jonathanalevi]

Dude… you would think that you might want to merge peoples PRs, we are trying to help improve your app and service… @matryer

[jonathanalevi]

@matryer Circling back a year later, I made some improvements to two other plugins, perhaps merge them?

[sprak3000]

@jonathanalevi

Looks like there is a conflict in your branch. Could you update it, and we'll see about getting this merged.

[sprak3000]

@jonathanalevi

You also need to run chmod +x on the script file you created.