Allowing public access to functions in field routines

Involves the following tracker items:
<a href="https://tracker.physiomeproject.org/show_bug.cgi?id=3299">Tracker Item 3299 Add publicly accessible field interpolate xi/Gauss routines</a>
<a href="https://tracker.physiomeproject.org/show_bug.cgi?id=3427">Tracker Item 3427 – OpenCMISS library feature: Allow users to access adjacent element information for a given mesh</a>
<a href="https://tracker.physiomeproject.org/show_bug.cgi?id=3545">Tracker Item 3545 – Add publicly accessible routines for getting line lengths</a>
<a href="https://tracker.physiomeproject.org/show_bug.cgi?id=3546">Tracker Item 3546 – Add publicly accessible routines for getting/setting scalefactors in fields using Hermite interpolation</a>
<a href="https://tracker.physiomeproject.org/show_bug.cgi?id=3587">Tracker Item 3587 – Add publicly accessible routines for updating field parameters given their dof number</a>
<a href="https://tracker.physiomeproject.org/show_bug.cgi?id=1998">Tracker Item 1998 – Implement Versions</a> (adds bug fixes and better error handling, however original tracker item is closed)