Change documentation (issue #7)

This version introduces multiple enhancements:

fixed require code in language file

Details of additions/deletions below:
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Modified:   /BLUE_FRAMEWORK/packages/CORE/error_class.php
            -- Modified --
               fatal method changed variable from polish to english
               other method changed variable from polish to english
               render method changed variable from polish to english

Modified:   /BLUE_FRAMEWORK/packages/CORE/loader_class.php
            -- Modified --
               changed code conventions
               added documentation

Modified:   /BLUE_FRAMEWORK/packages/CORE/meta_class.php
            -- Modified --
               changed code conventions
               added documentation

Modified:   /BLUE_FRAMEWORK/packages/CORE/module_class.php
            -- Modified --
               changed code conventions
               added documentation
               _checkRequiredLibraries changed deprecated method key_exists to array_key_exists

Modified:   /BLUE_FRAMEWORK/packages/CORE/option_class.php
            -- Modified --
               changed code conventions
               added documentation

Modified:   /BLUE_FRAMEWORK/packages/CORE/tree_class.php
            -- Modified --
               changed code conventions
               added documentation

Modified:   /BLUE_FRAMEWORK/packages/CORE/xml_class.php
            -- Modified --
               changed code conventions
               added documentation