Issue #2339151 by EclipseGc, tim.plunkett, Gábor Hojtsy, effulgentsia: Conditions / context system does not allow for multiple configurable contexts, eg. language types

Issue #2309715 by Gábor Hojtsy: Fixed Several views still say they depend on block module but not anymore.

Issue #2298319 by Berdir | ivanjaros: Fixed views.display.block.allow should be a sequence not a boolean.

Issue #2278541 by tim.plunkett, kim.pepper, Bojhan, EclipseGc: Refactor block visibility to use condition plugins.

Issue #2256679 by alexpott, tim.plunkett: Fixed Use config schema to determine which config entity properties to export regardless of whether they are public or protected.

Issue #2274175 by tim.plunkett, vijaycs85: Block plugin schema should be defined separately from the entity.

Issue #2158003 by Wim Leers, msonnabaum, effulgentsia, moshe weitzman: Remove Block Cache API in favor of blocks returning #cache with cache tags.

Issue #2080823 by alexpott, swentel, Wim Leers: Create API to discover content or config entities' soft dependencies and use this to present a confirm form on module uninstall.

Issue #2167623 by danilenko_dn, sidharthap, Nitesh Sethia, krishnan.n, aitiba, alexpott, ashwinikumar, Barrett, damiankloip, deepakaryan1988, foxtrotcharlie, ianthomas_uk, neetu morwani, nonsie, piyuesh23, Sharique, sivaji, sushantpaste, swentel, vijaycs85, YesCT: Add test for all default configuration to ensure schema exists and is correct.

Issue #2130811 by alexpott, Gábor Hojtsy, vijaycs85, sun, Wim Leers: Use config schema in saving and validating configuration form to ensure data is consistent and correct.

Issue #2043527 followup by Gábor Hojtsy: Fixed Theme name is included in block machine name but should be stored as a key instead.

Issue #1964254 by vijaycs85, YesCT | Gábor Hojtsy: Fixed Configuration schemas missing langcode and uuid at places.

Issue #1948884 by vijaycs85, YesCT, Gábor Hojtsy: Create configuration schemas for block and custom_block() modules.

Issue #1470824 by alexpott, sun: Fixed XML encoder can only handle a small subset of PHP arrays, so switch to YAML.