Split three new manual pages EVP_CIPHER_nid(3), EVP_CIPHER_CTX_ctrl(3),

Split three new manual pages EVP_CIPHER_nid(3), EVP_CIPHER_CTX_ctrl(3),
and EVP_CIPHER_CTX_set_flags(3) out of the excessively large and
unwieldy EVP_EncryptInit(3).  This causes a number of inaccuracies
and gaps to stand out, but i'm not mixing text changes or content
additions into this split.

Using very useful feedback from tb@ regarding what belongs together
and how important the various functions are.  I refrained from bothering
him with the complete patch, but he likes the general direction.