On range normalization, don't cut unless necessary. Only update d-t-m when something was cut.
Added more detailed debug output for range normalization
 - Replaced hard-wired DOM element node type constant values with the names of the constants. (Better readability)
 - Added detailed debug information to SerializedRange.normalize
 - When normalizing a SerializedRange, and looking for the start, don't choose the last position of the previous text element, but the first position of the current one. This avoid adding whitespace by accident.