Merge branch 't/remove_sb_compat'

Merge branch 't/remove_sb_compat'

This topic branch was cooking for over 4 months and should now be
ready for prime time. The patches break compatibility with earlier
versions, so we need to bump the version number real soon now.

	72ffa7 client: Only start stdin task for addblob commands.
	85a6ae Remove old stream cipher API.
	d1407f Allow addblob commands to create output.
	243e31 client: Remove client_recv_buffer().
	277ed4 client: Remove sb-compatibility code.
	36ba18 Reject non-sideband connections.
	6ca50b blob: Avoid zero sized memcpy().
	cf308c Fix typo in documentation of stdin_command().
	fdb9d2 blob: Simplify fd2buf().