translation problems (issue #116)

This version introduces multiple enhancements:

solved problems with translating error codes when similar language was chosen

Details of additions/deletions below:
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Modified:   /BLUE_FRAMEWORK/packages/CORE/lang_class.php
            -- Updated --
                _loadLanguage renamed to loadLanguage and changed to public access and removed some unused part of code
                setTranslationArray to use new name of loadLanguage method

Modified:   /BLUE_FRAMEWORK/packages/CORE/error_class.php
            -- Updated --
                _pack to use public method loadLanguage  from lang_class

Modified:   /docs/errors.md
            -- Updated --
                _loadLanguage renamed to loadLanguage in core_error_19 description