fix: PHP warnings triggered by the test suite

[alquerci]

The test should fail when a warning PHP error occurred.

Depends on

• #301

How to execute tests?

To make test passes, I apply the following dependencies:

• #293
• #270
• #301

Checkout the "bundle": https://github.com/alquerci/symfony1/tree/fixtest-fail-on-php-errors--dev

Then execute:

test/bin/test --dependency-preferences 'lowest highest'

What is done?

• Set consistent error_reporting to catch from PHP warnings and higher errors.
• [validator] Fix two kind of warning
• [mailer] fix the support for swiftmailler 6
  • An alternative with tests for swiftmailer fix #279
  • The default sfMailer transport for Switf v6 is Swift_SmtpTransport instead of Swift_MailTransport.
    • As Swift_MailTransport as been removed.
  • Use composer version of swiftmailler by default on test.
  • Add test without composer
  • Remove duplicated code for loading from submodule
• Update core autoloader, and apply 4 space indents.
  • data/bin/symfony symfony:test --trace --update-autoloader

What about the CI?

I try to put a PHP error_reporting directive, but the execution environment looks like different than docker.

Next steps

• notice
• strict
• deprecated

[alquerci]

@thePanz hey, I got it tests passes on GitHub action.

Let me know whether this PR has any chance to be merged.