v1.2.1

Changes since 1.2.0:

• add support for encapsulated pixel data reading [weanti]
• fix one-byte overread into struct padding [bgilbert]
• support single-frame DICOM images and allow BitsStored > 8 [tokyovigilante]
• fix error handling for string values over max length [arngaillard]
• add -w (show warnings) to dcm-dump and dcm-getframe [jcupitt]
• reduce seeks on file io [rvause]