Fix for loops display (issue #72)
This version introduces multiple enhancements:

Added message when loop is empty, example of that feature, fixed example of optional elements in loop
 and turn off removing loop content when some marker wasn't replaced by content

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

Modified:   /BLUE_FRAMEWORK/packages/CORE/display_class.php
            -- Added --
               _getGroupMarkerContent to return content of loop
               _getGroupMarker to return content of loop with start and end markers
            -- Modified --
               loop modified to handle new feature with empty data message
               clean temporary commented cleaning loop when some markers wasn't replaced

Modified:   /BLUE_FRAMEWORK/packages/CORE/display_class.php
            -- Modified --
               run to run empty loop

Modified:   /BLUE_FRAMEWORK/modules/modul1/layouts/layout1.html
            -- Added --
               example of messages when loop is empty
            -- Modified --
               example of optional data in loop

Modified:   /BLUE_FRAMEWORK/modules/modul1/lang/modul1_en-GB.php
            -- Added --
               translation for empty loop message examle

Modified:   /BLUE_FRAMEWORK/modules/modul1/lang/modul1_pl-PL.php
            -- Added --
               translation for empty loop message example