Added more modules to the SEE ALSO section of the POD

Updated Changes file accordingly.

Also bumped version in the code to v0.1.1.
Use Moose traits
Updated Changes [ci skip]
ignore_missing now read-only, fixed POD for default value
Immutable class
Explicitly require Test::Differences
Updated Changes [ci skip]
Added _path tracking of data structure
Changed Perl 5.10 operator
Merge pull request #1 from robrwo/devel

Changes for v0.1.1