Issue #1552412 by duellj: Make API links point to D8 version, and where possible make them future-proof

- Patch #1439692 by clemens.tolboom, plach, dawehner, das-peter, Gábor Hojtsy: Rename field language properties to langcode.

Issue #673224 by jhodgdon, aspilicious, rocket_nova: Fixed None of the hooks in field.api.php are grouped as such.

Nate Lampton authored Oct 30, 2011 and catch committed Nov 01, 2011

Issue #22336 by quicksketch, scor, boombatower, and rfay. Move all core Drupal files under a core subdirectory.

And the .install file for the test. You'd think I wouldn't forget that TWICE, but you would be wrong.

Issue #1190928 by droplet: Add examples of entity type in field_get_items() (and fix punctuation in other examples).

Issue #1138040 by barbi: Fixed hook_field_shema() doc has incorrect field type in format in example.

- Patch #1097972 by boombatower: Fixed hook_field_extra_fields_display_alter() incorrect example code.

#616240 follow-up by yched, dereine, marvil07: Make Field UI screens extensible from contrib - part II.

- Patch #902264 by Damien Tournoud: move hook_field_schema() to .install files so we can get the upgrade path to work.