Takes care of formats other that HTML

Fixes troywilliams/moodle-mod_dialogue#33
Added format support to dialogue_generate_summary_line

Fixes troywilliams/moodle-mod_dialogue#33
Merge pull request #34 from juancs/troywilliams_moodle-mod_dialogue33

Takes care of formats other that HTML
Setting version required to 2.8 alpha for developer testing
Replaced deprecated textlib calls with core_text calls
Removed old legacy permission code - deprecated
Remove deprecated show_button_group method in the renderer
Removed deprecated SHOW_ constants in dialogue manager class