backport changes to ciphers(1) man page

Backport of the patch:
add ECC strings to ciphers(1), point out difference between DH and ECDH
and few other changes applicable to the 1.0.1 code base.

 * Make a clear distinction between DH and ECDH key exchange.
 * Group all key exchange cipher suite identifiers, first DH then ECDH
 * add descriptions for all supported *DH* identifiers
 * add ECDSA authentication descriptions
 * add example showing how to disable all suites that offer no
   authentication or encryption
 * backport listing of elliptic curve cipher suites.
 * backport listing of TLS 1.2 cipher suites, add note that DH_RSA
   and DH_DSS is not implemented in this version
 * backport of description of PSK and listing of PSK cipher suites
 * backport description of AES128, AES256 and AESGCM options
 * backport description of CAMELLIA128, CAMELLIA256 options