Set default private keyfile

Hello,

I'm missing an option to set da default private keyfile, so that I don't need to manually add it all the time for each new session created.

You can set it as part of default session settings:
https://winscp.net/eng/docs/ui_login#defaults

Or you can load the key to Pageant.
https://winscp.net/eng/docs/ui_pageant