Merge error from 2a35f2f928059620aa55a41458af48c0effb8ced,
which was then further regressed by Sam running the text collector
on those faulty templates: 750b5b4079510ff1edc16dadf5a8b2a65258c072
Was inferred by the containing file previously,
which is deprecated behaviour, because it obscures
the fact that renaming an template file or copying
template code will change the context of the translations.
While it would be nice to use shorter and more readable namespaces,
this change would remove all existing translations.
Since there is no (easy) migration of entities to a new namespace,
having verbose template code is the lesser of two evils.
API CHANGE Removed ModelAdmin->ResultColumns()/ColumnSelectionField, selection of own fields no longer possible through the UI, to be replaced by a more generic GridField component
