New encryption algorith, CAST-128. Implementation by Steve Reid.

Rev: src/modules/_Crypto/CREDITS:1.3
Rev: src/modules/_Crypto/Makefile.in:1.14
Rev: src/modules/_Crypto/cast.c:1.1
Rev: src/modules/_Crypto/crypto.c:1.21
Rev: src/modules/_Crypto/precompiled_crypto.h:1.15
Rev: src/modules/_Crypto/testsuite.in:1.6