Allow import of private key from key file on Android

[Hooloovoo]

Thank you very much for Nebula, which I love and use across all my personal devices.

Unless I am missing it, the only way on the Android app to import a private key generated on another device is by copy-pasting the text, which was really annoying on a new device where I didn't have any text editors or secure way to send myself text. In the end I did it with a draft email on my webmail!

My standard flow for all my devices is to generate a key and certificate for all devices and then install them on all the devices. I therefore generated a .key and .crt on my master machine, copied those onto the device by USB and then spent far longer than I should have trying to import them. For many minutes I was trying to import the .crt and receiving the error:
Error loading certificate content
public key in cert and private key supplied don't match
I finally realised that you have to first hit the "Show/Import Private Key" button first, which puts it in a text box on the screen and then you have to highlight that and replace it with text from the .key file before you can then import the .crt file.