DiffieHellman: gracefully handle platforms that fail the sha256 self test, currently only known to be PowerPC. Added support for PHP's built-in hash functions (they were added in 5.1.2) and use them in lieu of the built-in sha256 implementation when available.

form.searchform, td#cell-sbleft {
	background-color: #2b2b2b;
	background-image: none;
}