Simplify message data handling when building MIME message.

Use Horde_Stream, only convert in one place, reduce memory usage.

Conflicts:
	framework/ActiveSync/lib/Horde/ActiveSync/Imap/Adapter.php
phpdoc
Use Horde_Stream_Temp
No need to dereference the stream, Horde_Stream can handle it.
Still need to return a resource.
Use Horde_Stream methods.
Horde_Stream#getString() does not work the way I thought.
Use Horde_Stream

Conflicts:
	framework/ActiveSync/package.xml
Typos.
More places to use Horde_Stream
Horde_Stream#read() doesn't exist
Typos
Another typo
Fix merge.
Horde_Stream#substream() feels more natural here.
$this->_decoder->getStream() returns a Horde_Stream, not resource.

Bug: 12727
Merge branch 'master' into as_streams

Conflicts:
	framework/ActiveSync/package.xml
Merge branch 'master' into as_streams
Merge branch 'master' into as_streams
Merge branch 'master' into as_streams