throw consistently all errors into exceptions
Placeholder and emptyText fixes, little bit of PSR-2

1) no more default emptyText message for Model field
2) set default_empty_text message for ValueList fields
3) PSR-2 of ValueList
4) set ValueList as actually abstract class
5) simplify ValueList->getValueList()
ValueList: use normalize() instead of loadPOST()

That doesn't change much, but should be more correct to do this way. loadPOST() is more like "internal" or "core" method, but normalize() is function meant for customization.
Merge pull request #399 from DarkSide666/master

Placeholder and emptyText fixes, little bit of PSR-2
Merge pull request #398 from rvadym/master

setCaption for column
Merge branch 'pr/395'
Merge branch 'master' into pr/395
Merge branch 'pr/395'
Merge branch 'master' of github.com:atk4/atk4
Update MVCForm.php
Update MVCGrid.php
Merge pull request #401 from DarkSide666/patch-2

Timepicker -> Time, daytime -> time
hide _id field in mongo
Enable custom mandatory html code
Merge branch 'master' of https://github.com/atk4/atk4
Strange case - missing e->shift caused very fatal error
MVCForm: we don't need "Please select" option if model field is mandatory anyway
Model: comment typo
Update Basic.php
Update Advanced.php