Fix issue #731
Fix issue #723, plus add support for relative date/times in FieldtypeDatetime's output format options (see them in Time Format).
Fix issue #722 - better error message when attempting to add a template that already exists
Fix issue #728 - better error messages when trying to save a field with no name
Various minor fixes
Meant to include this minor fix in last commit as well.
ProcessWire 2.5.5 update which introduces new module configuration options. See https://processwire.com/blog/posts/new-module-configuration-options/ for more info.