Removed unused CalculateDigest and CalculateDigestInternal functions.
Fix up digest comments.
Use double sha256 instead of SAMY. Call it HASH256.
Removed unused HashAlgorithm1, HashAlgorithm2,
XOR(), and related config entries.
Fix up comments; remove all instances of "samy".
Removed var bReturnValue.
Merge pull request #389 from benma/hashdigests_doublesha256

Remove SAMY and WHIRLPOOL, use double SHA256 instead
OTCheque: rename class to Cheque
OTCheque: rename files to Cheque.{h,c}pp