New function to just load the summary. Not much use yet, until unread

New function to just load the summary. Not much use yet, until unread

	* camel-folder-summary.c (camel_folder_summary_header_load): New
	function to just load the summary.  Not much use yet, until unread
	counts are stored in the summary (which now looks like too much
	work!).

	* camel-mime-utils.c (header_decode_mailbox): Crappy fix for
	stupid mailers.  If we get 'name b. name <foo>' then treat it as
	'"name b. name" <foo>'.  See 8147.
	(header_decode_mailbox): Another fix for really broken mailers
	that have things that look like addresses followed by <address>
	bits.
	(rfc2047_encode_word): Escape ??= to avoid some bizarre warning
	about trigraphs.

	(scan_dir): If we dont have the folder open, then scan the 'new'
	and 'cur' folders for new and unread messages to count instead.