Fix #88

This has been obsolete a long time

Ref #112

Ref #109

Don't be a jerk when card database isn't usable.

Added Mac OS X build instructions.

Better error message and allow the user to still connect

Ref: #102

Mtgjson importer (fixes #84)

It will be saved only if:
* it’s different than the default (the user used a custom url);
* the download actually worked

By default oracle saves cards.xml to the correct path, where cockatrice
will be able to pick it up;
if oracle is not able to determine the path or the user unchecks the
option, oracle will ask for a save path

Merge branch 'mtgjson-importer' of https://github.com/Daenyth/Cockatrice into Daenyth-mtgjson-importer

Add HQ card option