Using the delete key in the content area of the RadEditor sometimes cause incorrect behavior to be encountered, e.g., content disappearance, incorrect elements to be removed etc.

For example pressing delete key before a list element, the li tag is removed, instead of just the cursor to be positioned in it.

This behavior comes from the browser and there is no RadEditor logic that interferes with it.

It would be nice if this inconsistencies are handled via custom commands that act more stable across browsers. 

The following issues are fixed with this item:

Pressing backspace in a table sometimes inserts non breaking spaces
Could not complete the operation due to error 800a025e when deleting table columns
Redundand nbsps are added to the content using backspace inside <ul> in IE9
IE10 crashes when nested lists are highlighted and deleted
Incorrect List nesting is generated when a Paragraph is deleted via backspace key under IE11