Change documentation (issue #7)
Change code convetion in all files (issue #6)

This version introduces multiple enhancements:

Configuration files and main language files.
All documentation changed to english language, and written missing documentation.
Also changed some code convention in the same files.

Details of additions/deletions below:
--------------------------------------------------------------

Modified:   /BLUE_FRAMEWORK/cfg/dtd/config.dtd
            -- Modified --
               changed code conventions
               added documentation

Modified:   /BLUE_FRAMEWORK/cfg/dtd/meta.dtd
            -- Modified --
               changed code conventions
               added documentation
               changed documentation from polish to english

Modified:   /BLUE_FRAMEWORK/cfg/dtd/tree.dtd
            -- Modified --
               changed code conventions
               added documentation
               changed documentation from polish to english

Modified:   /BLUE_FRAMEWORK/cfg/lang/core_error_en-GB.php
            -- Modified --
               changed code conventions
               changed documentation
               changed documentation from polish to english
               translated errors to english

Modified:   /BLUE_FRAMEWORK/cfg/lang/core_error_pl-PL.php
            -- Modified --
               changed code conventions
               added documentation
               changed documentation from polish to english

Modified:   /BLUE_FRAMEWORK/cfg/lang/core_error_en-GB.php
            -- Modified --
               changed code conventions
               added documentation
               changed documentation from polish to english
               translated errors to english

Modified:   /BLUE_FRAMEWORK/cfg/lang/core_pl-PL.php
            -- Modified --
               changed code conventions
               added documentation
               changed documentation from polish to english

Modified:   /BLUE_FRAMEWORK/cfg/config.xml
            -- Modified --
               changed code conventions
               added documentation
               changed documentation from polish to english

Modified:   /BLUE_FRAMEWORK/cfg/meta.xml
            -- Modified --
               changed code conventions
               added documentation

Modified:   /BLUE_FRAMEWORK/cfg/tree.xml
            -- Modified --
               changed code conventions
               added documentation