* Better support Double-Faced Cards
This patch allows cards to be (virtually) transformed into other cards
while preserving their state, essentially implemeting the MTG mechanic
of the same name.
On the server side, this is implemented by allowing cards to be "stashed
away". A card that is stashed away is not in any zone, but is instead
owned by another card. When a token is destroyed due to a zone change,
if it had a card stashed away, that card is placed in the target zone
instead of the token.
On the database side, `attach="transform"` is used on `<reverse>` and
`<reverse-related>` to indicate that the created token should be
transformed this way.
Old servers ignore the new field in `Command_CreateToken` and will
perform a regular attachment, as currently.
* Address review comments
* Prevent tokens from being stashed
* format.sh
* add proto files to clangify
* apply clangify to proto files
* remove blocksonsingleline, it didn't actually do anything
also add missing space to the travis warning, emoji are monospace too
That marker is only recognized by pb3-compatible compilers, meaning that
tools which are otherwise compatible with our files break on them.
Notably, this includes hprotoc (for haskell).
