Fixed typo in comment.
Fixed wrong validation of PN, LO and SH values.

According to DICOM PS 3.5, the control characters LF, FF and CR are not
allowed for LO and SH element values. Also ESC is only allowed for ISO 2022
encoding (escape sequences), but not for the default character set (ASCII).
Added check for requirements clarified by CP-1401.

Added check to read() and write() method and report a warning message if the
Completion Flag is not "COMPLETE" for X-Ray Radiation Dose SR objects.
Updated data dictionary for DICOM 2014c edition.

Updated data dictionary for the latest edition of the DICOM standard,
which has been released on 2014-11-21.
Added support for new UIDs from DICOM 2014c.

Added support for new SOP Class UIDs from Supplement 171 (Unified Procedure
Step by REpresentational State Transfer Services) and Supplement 172
(Parametric Map Storage). Also updated name of well-known UPS SOP instance.