Fixed handling of empty parts in multipart messages
Fixed recovering of invalid content type "text/"
Added handling for "binary" encoding:
"
Content-Type: image/jpeg; charset=binary;
 name=image._jpg
Content-Disposition: attachment;
 filename=image._jpg;
 size=389291

/9j/4AAQSkZJRgABAQEAyADIAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0a
"
Fixed issue with multiline header value in base64 encoding with tabs inside:
"Disposition-Notification-To: =?windows-1251?B?ZWFzdXJlLg\r\n"
				+ "\t==?=\r\n"
				+ "\t<user@server.domain>\r\n"
Fixed issue with multiline header value in base64 encoding with spaces inside:
"Disposition-Notification-To: =?windows-1251?B?ZWFzdXJlLg\r\n"
				+ " ==?=\r\n"
				+ "\t<user@server.domain>\r\n"
implemented handling of invalid "Charset" parameter in Content-Disposition:
Content-Disposition: attachment; charset=windows-1251; filename="image.jpg"
Implemented parsing of the DateTime with year at the end and TimeZone in parenthesis: "Tue Feb 18 10:23:30 2014 (MSK)"
Added MessageInfo class which combines message number, unique identifier and size (the information we can get before downloading actual messages).
It is useful since it is easier to keep correspondence between these three info items.
Fixed behavior of GetMessageInfos method after message deletion. Message numbers now have correct gaps in sequence numbers:

UIDL
1 id1
2 id2
3 id3
.
DELE 2
+OK
UIDL
1 id1
3 id3
.
Merge pull request #7 from IlyaGerasimets/master

Multiple fixed of various problems after testing on 50000 production emails