You should already be able to see them. For FTP connections, you need to enable the "Show hidden files" option in the FTP connection's settings. You can edit the connection's settings by tapping on the blue arrow on the right side of the connection.

I'm considering adding Multimarkdown preview support in the future.

Can you please have a look at the server log file? It should have an error message.

Thanks!

I added png and jpg files because people wanted to be able to open them in Textastic so they can upload it to a server. Obviously they shouldn't be registered as plain text files. I'll change that.

Just use the remote preview feature. You can enter an arbitrary url there.

Well, Textastic tells the system that all the programming files like .html, .cpp etc. are plain text files. Those editors claim that they can open plain text files. That's why they appear in the list.

No, there is no official API from Apple for shortcuts like that.

It should be even easier with ssh-keygen.

You can use a command line like this to import (-i) your pem file and convert to OpenSSH format:

ssh-keygen -i -f infile.pem > outfile

You could try this tip from the manual:

Puttygen should also be able to load the .pem file using the Conversions - Import Key menu item.

"Textastic expects the key file to be in the format used by the OpenSSH utility "ssh-keygen". If you instead have a key in PuTTY's format (.ppk), you can use PuTTYgen to convert it to OpenSSH format:

Visit the PuTTY website and download puttygen.exe (on your PC). Open it, and using the File menu, load your .ppk that you already use, and type in your passphrase. Now go to the Conversions menu and export the key as an OpenSSH key. You can now use the converted key with Textastic."