Maintain a list of metadata mappings outside of the script

*Title*
maintain a list of metadata mappings outside of the script

*Detailed description*
A PHP script invoking exiftool which returns a PHP array.
This array is used to fill in an XML template, which can be edited at will.
Outside metadata is contained in a .ini file, which is very easy to maintain. The script needs to be invoked with a single filename or a single foldername and the name of the output XML file.

*Solution Champion*
[~techmaurice]

*Corresponding Issue(s)*
[SPR:How to maintain a list of metadata mappings outside of the script]

_Add an entry to the OPF Tool Registry, and provide a link to it here._

*Evaluation*
_Any notes or links on how the solution performed._