#1395320 by dereine: Allow to use list human readable values instead of only machine key in argument summaries

#1303398 by johnv: Some entities might have a certain field value just empty but it's set, which caused notices

If you have added a field before a language you have LANGUAGE_NONE as field key,
but you current site language is for example 'en'. So add LANGUAGE_NONE as possible value for a field.

Issue #1188500: Provide a reverse relationship on term reference fields and a generic entity reverse relationship handler so anyone can use it.

#1070744 by derhasi, dagmar, bojanz, kdebaas, jamsilver, dereine ...: Fallback to a existant language when render a fieldapi field

Issue #1089694: Fix group by on field api with multiple field values by allowing group by on entity id for these fields.

#1149712 by bojanz: Bring additional informations into field formatters: row_id, view, and the field itself