(indentation in next commit)

In reality, it should be done by internally only using changeState, but that's another story

It seems the commit reimplement a kind of adhoc changeState

- Allow to continue to edit a form while saving is on going
- Reset fields on form view update (like by clicking on the active tab from the panel)
- Fix rendering an input like gadget with the same value as rendered before causes the
  gadget to be not updated even if the field has been manually edited.

/bug #20190204-39AF19
https://nexedijs.erp5.net/#/bug_module/20190204-39AF19

/reviewed-on nexedi/erp5!861

This reverts commit b7f126bd.

This reverts commit 2cfc0ed0.

This reverts commit 002b97ee.

This reverts commit 9929bc4f.

Revert "DATETIMEFIELDUPDATE Add testFormViewEditableNextWithEditedField testFormViewEditableSaveActionContinuingEditing + update testDateTimeFieldUpdate"

This reverts commit a815470c.

This reverts commit 7c386987.

This reverts commit b8a54f81.

This reverts commit 7bd22168.

This reverts commit 5c79470a.

This reverts commit 98101f69.

This reverts commit 65480a09.

For instance, typing a backslash in a relation field does not crash the ui anymore.

/bug #20180123-D78557
https://nexedijs.erp5.net/#/bug_module/20180123-D78557

DATETIMEFIELDUPDATE Add testFormViewEditableNextWithEditedField testFormViewEditableSaveActionContinuingEditing + update testDateTimeFieldUpdate

                                     version   | generique       | render               | onchange            | onmodification      | ideale
have A and B with empty reference,               keep typed        field reset to empty   keep typed            ?                     field reset empty
goto A, click next to acces B,
type in reference while B form is loading,
B is loaded

same with B reference = 1                        field set to 1    field set to 1         field set to 1        ?                     field set to 1

have A with empty reference,                     keep typed        field reset to empty   field reset to empty  ?                     field reset to empty
type in reference (hello),                       (hello)           ()                     ()                    (?)                   ()
click View on confirm popup,
A is reloaded

have A with empty reference,                     keep typed        field reset to empty   field reset to empty  ?                     field reset to empty
click View to reload the form,                   (hello2)          ()                     ()                    (?)                   ()
type in reference (hello2),
A is reloaded

have A with empty reference,                     keep typed        field reset            field reset           ?                     keep typed (the form decides
to update the field but should not ? no)
type in reference (hello), save,                 (hello2)          (hello)                (hello) (why??)       (?)                   (hello2)
type in reference (hello2),
focus something else,
A form is reloaded

have A with empty reference,                     field reset       field reset            field reset           ?                     field reset (user should see
the modification done server side)
type in reference (hello), click save,           (world)           (world)                (world)               (?)                   (world)
type in reference (hello2),
focus something else,
interaction add modifications to the reference
(world),
A form is reloaded

------------------------------------
So !

input.value MUST be updated on onStateChange if modification_dict.hasOwnProperty("value")
this.state.value MUST be updated on getContent
this.state.value MUST be updated on onEvent change

------------------------------------
UNRELATED NOTES

input.value reflects the typed value of the element
gadget_input.getContent reflects the typed value of the element too

input.value = "hello" replaces the current value to "hello", no matter the state of the input
gadget_input.render({value: "hello"}) does not... because gadget.state.value does not really reflects the dom value.
  if gadget.state.value was reflecting the value, then
gadget_input.render({value: "hello"}) reflects the current value to "hello", no matter the state of the input

so the form could act : while saving, listen for changes/inputs, (now saved) get the new form but ignore it, put save to orange if changes/inputs were done

rendering the gadget with the same value as rendered before causes the
gadget to be not updated even if the field has been manually edited.

/bug #20190204-39AF19
https://nexedijs.erp5.net/#/bug_module/20190204-39AF19

checkValidity calls getContent, which uses the same mutex