strip any trailing dots when resolving IDs

fixes #4072

code style: line breaks

codestyle adjustments: class declaration braces

Apply rector fixes to inc/File

Replace check for null with cast to string

Fix: 'E_WARNING: Uninitialized string offset -1' on some templates

Update core code to make use of sexplode()

This makes use of our own explode mechanism everywhere were we expect a
fixed number of results.

move resolvers into File namespace