Making quick open more flexible (#76 - @kidonng)

Before, fzf.fish would only prepend ./ if the command line was empty and the selected path is a directory.
Now, prepend ./ gets prepended even if the user has some input and even if the selected directory is not a directory so that

• if the path is an executable, the user can hit Enter one more time to immediately execute it
• if the path is a directory, the user can hit Enter one more time to immediately cd into it

Fixed multi-line command bug (8bacfb3)

Before, selecting a multi-line command when using the search command history feature would result in the command lined being replaced with only the top line of the selected command.
For example, selecting this command from history

function example
    echo "This is just an example"
end

would result in the command line becoming only

function example

The bug is now fixed so users can recall the entirety of multi-line commands from history.