Add a code check tool at server initialization

[kenashkov]

This tool should check for:

• "==" - comparison should always be done with "==="
• all files must have declare(strict_types=1);
• more to be added in future...

[kenashkov]

Work in branch V_0_0_6. Add a new public stsatic method in Guzaba2\Kernel\ClassDeclarationValidation::check_source()

[ronald-hristov]

Added in master