Introduction
------------

In MSWord, you can create a formula field (starting with =).
When you save your file as `docx`, this `FORMULA` field is registered
in you file (a field starting with `=`). In its current state,
LibreOffice can't parse the `FORMULA` field in `docx` file.

Context of this fix
-------------------

This fix is entirely located in the `DomainMapper_Impl.cxx` file
because it's where the parsing is done.

How this fix works
------------------

First, we add `FORMULA` support by adding it to the `aFields[]` variable.
Next, to handle the `FORMULA` constant, we add a condition (swith case) in
`DomainMapper_Impl::CloseFieldCommand()` to call `handleFieldFormula`.

Note
----

In function `lcl_ExtractToken`, if command starts with `=`, it's a
`FORMULA` field.

Change-Id: If7d25de5413aa3133b22523d8a3f34ab6961adfc
Reviewed-on: https://gerrit.libreoffice.org/34334Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>