Reimplemented Form Validation

[romaninsh]

New validation now is in line with the Agile Data 1.2 release. Define validations at the model level for multiple fields!

Several other validation ways are depreciated and some major changes which is why we'll pack this into UI 1.2.

• form->setModel() will automatically save() data when submitted, because ... why not?
• form->onSubmit() can execute error as before.
• form->validate hook is no longer there, so we must review code to make sure it's not used in some field.

See if we can address the following issues with this PR:

• // moved to Big addColumn, addField and Seed refactor (PART1) #179 - Create consistent addField(data_field_spec, form_field_spec) + test scripts
• Submitting form with "Enter" creates two records #173 Enter - two records
• Form not loading boolean value in a checkbox #155 boolean not working
• Form - unable to 'un-tick' check-boxes #130 unable to un-check box
• Form integration demo - "Check Duplicate" does not seem to be implemented #127 implement "Check Duplicate"
• disabled does not work when adding field into form #126 "disable" does not work.
• Forms don't respect field caption #106 captions respected , should probably be solved
• Refactor form->success() to rely on Message class #102 success to use Message template

[DarkSide666]

This will not work always. Sometimes tryLoadBy will load current record first and not even check if there are more records. So it's better to do this with conditions something like:

$c = clone $this;
$c->addCondition('name', $this['name']);
$c->addCondition($c->id_field, '<>', $this->id);
$c->tryLoadAny();
if ($c->loaded()) {
    $errors['name'] = 'Country name must be unique';
}

[DarkSide666]

this still is not 100% safe way to check name uniqueness.
what is name already is not unique in database?

[DarkSide666]

... variable $form not $f

[DarkSide666]

typo - linking

[romaninsh]

I'm leaving other fixes for later.