cfunction
(buffer/bit buffer index)
Gets the bit at the given bit-index. Returns true if the bit is
set, false if not.
(buffer/bit (buffer/new-filled 1 (chr "0")) 4)
# => true
(buffer/bit (buffer/new-filled 1 48) 4)
# => true
(buffer/bit @"0" 4)
# => true
(buffer/bit @"1" 0)
# => true