Add a changelog dialog to show the user the new features

[jguerinet]

No description provided.

[AllanWang]

I know we talked about this a while back. I have an xml to changelog function that you can copy (and probably reformat if you aren't using MaterialDialog).

I also ended up writing a gradle function that can convert the xml code to markdown so that it can be properly viewed on github as well

[jguerinet]

There's still a bit of the code from when we started this left over. But yeah, I'm hoping to get this feature back up and running soon (I'm just in the middle of a huge refactor).

[jguerinet]

Also @AllanWang I'm devoting a bunch of time to cleaning this project up next week, it's been a big mess ever since I Kotlinized + modernized so the codebase should be much nicer to look at and work with then!