Add some Debian files to .gitignore

And remove the entry for Emacs, which doesn't work due to being a comment anyway.
Less aggressive ignoring of vim swap files

It's a rare sight to see non-.swp swap files anyway, and we don't want
other files (e.g. .sql) being accidentally ignored.
Add nano.save to gitignore
Add .pyd to gitignore [skip ci]

.pyd is a rare sight, but I added it just to be on the safe side.
Merge pull request #554 from nyuszika7h/debian-gitignore

Add some Debian files to .gitignore