btrfs

* Fixed coding style for all files under /src/add-ons/kernel/file_systems/btrfs
* rewrote crc_table.cpp to generate CRCTable.cpp that conforms to coding style.

Change-Id: I90fcc143320c7a7e9a6dc174f0ad82f40bb8a9b6
Reviewed-on: https://review.haiku-os.org/c/1194
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

BTRFS: Add author and license.

Signed-off-by: Augustin Cavalier <waddlesplash@gmail.com>

BTRFS: Implement a simple journaling approach, this is not finished and mostly satisfy the need for passing Transaction object for many functions.

Some details about the current Journal:
* Journal can only end transaction.
* It holds a transaction id of fs (fCurrentGeneration) that increments each time a transaction starts.
* _TransactionWritten now just printing message.

Signed-off-by: Augustin Cavalier <waddlesplash@gmail.com>