Revision 894750

Added malformedHeaderStartsBody boolean option to MimeEntityConfig (MIME4J-58)
Added unread(ByteArrayBuffer) method to LineReaderInputStream, only implemented by BufferedLineReaderInputStream.
MimeEntity parseField now optionally unread the field (when in lenient mode). If the unread fails it throws an exception.
Improved IllegalArgumentException handling in MimeBoundaryInputStream (boundary vs buffersize is more secure than before).
MimeBoundaryInputStream.fillBuffer had a bug (while i > 0) replaced with (while i > buffer.pos()). It was never hit because of current "refill" behaviour.
BufferedLineReaderInputStream now supports unread(ByteArrayBuffer): the unread simply put the passed buffer in place of the original buffer and consume it. The first time fillBuffer is called and the buffer is completely consumed the old buffer is restore. If fillbuffer is called before the buffer is consumed we throw an exception (never happens for the current refill behaviour, but protect future changes with an explicit exception).