connected should be bool, not Bitboard

connected should be bool, not Bitboard

There's no reason to define it as a Bitboard, so for consistency, use bool.

This is even a speedup on my machine: i7-3770k, using gcc 4.9.1 (linux):

    stat        test     master    diff
    mean   2,341,338  2,327,998  13,134
    stdev     15,765     14,717   5,405

    speedup       0.56%
    P(speedup>0) 100.0%

No functional change.

Resolves #298