Dicom Versions Save

• write: pad certain VRs with spaces instead of null bytes (#81)
• Close file explicitly on error in NewParserFromFile (#76)

• Add ISO_6 character encoding
• Option to skip VR verification on write
• Use go modules instead of dep.

Minor internal changes and bugfixes (mostly around printing of DICOM metadata).

The latest modern release of dicomutil after many refactors and improvements. Future releases will include more descriptive change lists, but this is the first major release including binaries and including many of the changes added in this fork.