find_bishop_attacks: Find set of bishop attacks
In eduardokapp/chessR: R Chess Engine

Given a board state, a side and the bishop position, return every attacked squares by that bishop.

1	find_bishop_attacks(board, whites, square, queen = FALSE)

`board`	A 12 by 64 binary matrix representing the game current status.
`whites`	If TRUE, the piece is a white piece, else blacks.
`square`	A character representing a square ("a1" to "h8").
`queen`	Internal parameter to be used when calculating queen moves. If TRUE, ignores the fact that no bishop exists in that position.