Add a button to switch languages

[Mephodio]

For some reason, the button to switch input and output languages doesn't work in the application (but it does work on the website), so I tried to work around that. It's a dirty solution, but maybe you can do something with it.

[sakusaku3939]

Thanks for the pull request! Just before I do a review, where is the button to switch languages in the web version?

[fm-sys]

BTW, what about using the material swap icon instead of "S"?

https://fonts.google.com/icons?selected=Material%20Icons%3Aswap_vert%3A

[Mephodio]

Where is the button to switch languages in the web version?

I did some tests, and turned out that only desktop version has this button (even when opened on a small screen, which confused me):

BTW, what about using the material swap icon instead of "S"?

Yep, my button looks ugly, and now i came up with another idea: instead of native button, add an html button from the desktop version. I'll try to implement this.

[Mephodio]

Now it looks better :)

[sakusaku3939]

It looks good.:+1: I did not want to add native buttons as much as possible. Thank you!