Issue #2751223 by maxocub, jeroenbegyn, Gábor Hojtsy, Jo Fitzgerald: D6 & D7 users are migrated into D8 with incorrect langcode

Revert "Issue #2560795 by mikeryan, phenaproxima, penyaskito, willwh, benjy: Source plugins have a hidden dependency on migrate_drupal"

This reverts commit 89815ba3.

Issue #2560795 by mikeryan, phenaproxima, penyaskito, willwh, benjy: Source plugins have a hidden dependency on migrate_drupal

Issue #2625696 by chx, benjy, alexpott, catch, mikeryan, andypost, phenaproxima: Make migrations themselves plugins instead of config entities

Revert "Issue #2625696 by chx, alexpott, benjy, mikeryan, andypost, phenaproxima: Make migrations themselves plugins instead of config entities"

This reverts commit 694994fe.

Issue #2625696 by chx, alexpott, benjy, mikeryan, andypost, phenaproxima: Make migrations themselves plugins instead of config entities

Issue #2484405 by phenaproxima, quietone, neclimdul: User pictures do not need a dedicated process plugin

Issue #2414651 by phenaproxima, quietone, miguelc303, mikeryan, benjy: Migration Files for Drupal 7 Users