Chess: Add ability to export game as PGN file

This patch adds an option to the menubar for exporting the current
game as a PGN file. This file can then be read by other chess
programs (and ours eventually) to replay the game or analyze it.
The implementation is mostly PGN spec compliant, however the code
could use some more work. Particularly the `const_cast`s...
But it's a start. :^)

Fixup: Chess: Fixed hard-coded home path in unveil() call

Fixup: Chess: Removed castling flags from Move struct

The castling detection logic is done inside Move::to_algebraic()
now, removing the need for is_castle_short and is_castle_long flags
inside of the Move struct.

0 files changed, 0 insertions, 0 deletions