moved SHA1::Digest class to SHA1Digest to allow forward declarations

applications/test/sha1/testSHA1.C

src/OpenFOAM/db/IOstreams/hashes/OSHA1stream.H

src/OpenFOAM/db/dictionary/dictionary.C

src/OpenFOAM/db/dictionary/dictionary.H

src/OpenFOAM/primitives/hashes/SHA1/SHA1.C

src/OpenFOAM/primitives/hashes/SHA1/SHA1.H

src/OpenFOAM/primitives/hashes/SHA1/SHA1Digest.C

src/OpenFOAM/primitives/hashes/SHA1/SHA1Digest.H

src/OpenFOAM/primitives/hashes/SHA1/SHA1I.H