Made Ctrl-V importer work more robust.

Hi,

This is a fix to ctrl-V importer so it supports card spellings like with a few regexps:
* Aetherling
* Ætherling
* Rough & Tumble
* Turn/Burn
* Sphinx’s Revelation

And also supports "Sideboard" line to indicate where sideboard begins. (commonly seen as "SIDEBOARD", "Sideboard:", "Sideboard (15)" etc.)

I wrote this as a standalone script before [ at https://github.com/taw/mtg ], but it's better to just integrate it with cockatrice.

I can't think of any issues that might cause.