Another (and hopefully last) major streams commit.

This moves unicode conversion to the filter layer
(rather than at the lower streams layer)
unicode_filter.c has been moved from ext/unicode to main/streams
as it's an integral part of the streams unicode conversion process.

There are now three ways to set encoding on a stream:

(1) By context
$ctx = stream_context_create(NULL,array('encoding'=>'latin1'));
$fp = fopen('somefile', 'r+t', false, $ctx);

(2) By stream_encoding()
$fp = fopen('somefile', 'r+');
stream_encoding($fp, 'latin1');

(3) By filter
$fp = fopen('somefile', 'r+');
stream_filter_append($fp, 'unicode.from.latin1', STREAM_FILTER_READ);
stream_filter_append($fp, 'unicode.to.latin1', STREAM_FILTER_WRITE);

Note: Methods 1 and 2 are convenience wrappers around method 3.

ext/unicode/php_unicode.h

@@ -67,7 +67,6 @@ PHP_FUNCTION(collator_get_attribute);
 PHP_METHOD(collator, __construct);
 
 void php_init_collation(TSRMLS_D);
-extern php_stream_filter_factory php_unicode_filter_factory;
 
 #ifdef  __cplusplus
 } // extern "C"