pry/pry — pull request #750 by mickey (2012-11-09 13:36:30+00:00)
Title: save-file's filename argument should be optional

This should fix #735.
There could be some rough edges, please let me know if you want to change anything.

Here's an example session to demonstrate how it works:

```
➜ pry git:(master) ✗ rake pry
[1] pry(main)> def toto ; puts 'toto'; end
=> nil
[2] pry(main)> save-file -m toto
/home/mike/pry/toto.rb successfully saved
[3] pry(main)> def titi ; puts 'titi'; end
=> nil
[4] pry(main)> save-file -m toto
/home/mike/pry/toto-1352467752.rb successfully saved
[5] pry(main)> save-file -m toto -m titi
/home/mike/pry/toto-titi.rb successfully saved
[6] pry(main)> save-file -m toto -m titi toto_and_titi.rb
/home/mike/pry/toto_and_titi.rb successfully saved
[7] pry(main)> save-file -m toto -m titi /tmp/tmp.rb
/tmp/tmp.rb successfully saved
[9] pry(main)> Pry.config.save_file_path = "~/tmp/pry"
=> "~/tmp/pry"
[10] pry(main)> save-file -m toto -m titi
The save-file path /home/mike/tmp/pry doesn't exist.
You can edit it in Pry.config.save_file_path
Would you like to create it ? [Y/n]
Y
/home/mike/tmp/pry/toto-titi.rb successfully saved
```