refactor #287 [Core][RFC] Refactor/date types (sstok)
refactor #287 [Core][RFC] Refactor/date types (sstok)

This PR was squashed before being merged into the 2.0-dev branch.
labels: bc-break

Discussion
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| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | yes
| Deprecations? | no
| Tickets       | n/a
| License       | MIT

This makes the model-format of the Date(Time) types immutable, and removes support for HTML5 input format for norm-input (which is actually less flexible than RFC3339).

Commits
-------

b37912f22784d4576d487501f0b61420131072d0 [Core] Make the value of DateTime types immutable
ba9cb62437494658aabdd3490cabf70b5a1f53e6 [Core] Remove support for HTML5 datetime

rollerworks/search-api-platform