Fixed normal text toolbar

Fux bugs

Fix bug with toolbar option
Fix buttons bug, when in buttons you set string it could throw error
Fix bug with fixed height option
Fix bug in Enter plugin and fix bug in ContextMenu module
Cover test selection module
Fix onchange event. When mode was changed it could call onchange with seletion markers
Fix fug in readonly mode then buttons not has disable
Now you can set value to editor using magic propery editor.value = ''
Fix last bugs in backspace plugin
Fix a lot of bugs with backspace keypressing inside inline elements
Fix a lot of bugs with backspace keypressing