In lieu of dropping in next release. We needed this in order to write
some unit-tests for exifcommon functionality, and this is common
functionality anyway (by any definition of common thus far).
- common/ifd.go: Added NewIfdIdentityFromString. The above allowed us to
cover this with unit-tests.
- This was required for go-exif-knife, to get IFD-paths from the
command-line.
Dustin Oprea