delete_text
Description:
Deletes text from an EditableText object, without copying the excised portion into the system clipboard.
see: cut_text
Parameters:
| this | a pointer to the EditableText object to modify. | 
| start_pos | a int indicating the starting character offset of the text to delete. | 
| end_pos | a int indicating the offset of the first character past the end of the text section to be deleted. | 
Returns:
| 
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