- added second signature for PDF-2 style header (this can be improved);
- added support for PDF-2 headers to `PdfHeader`; and
- more work required on valid major/minor version combinations.

- refactored `PDF-hul` PDF Header parsing, particularly the version parsing;
  - no more `null` return handling, specific exceptions are thrown instead;
  - these are caught and handled in the `PdfModule` class;
  - new `PdfVersion` class to handle version parsing and comparison;
  - PDF version detection now handled by pattern match, with better reporting of errors;
  - offsets added to `PdfException`s that were in the scope of refactoring;
  - added new `%PDF-2.` signature to the `PDF-hul` module;
- new `edu.harvard.hul.ois.jhove.messages.JhoveMessages.getMessageInstance` convenience method to clone message with sub-message;
- added two new test cases to `PDF-hul` regression tests for header version detection;
- added necessary `sed` insertions and file copies to handle changed integration test results to `jhove-bbt/scripts/create-1.33-target.sh`; and
- refactored "not found" reporting for modules and handlers in jhove-apps `edu.harvard.hul.ois.jhove.Jhove` class.

Error messages changed to give more detailed information:

- `PDF-HUL-137`:
- `PDF-HUL-148`: No longer mentions specific minor versions but has a more detailed sub-message
- `PDF-HUL-155`: Reports the header that was too short

New Error Messages:

- `PDF-HUL-160`: IOException reading PDF header
- `PDF-HUL-161`: PDF major version number should be 1.x or 2.x
- `PDF-HUL-162`: Malformed PDF version number

- moved field declarations.