Fix issues related to trying to erase lengths of zero.  NB: This is basically to allow an out of range index so long as the operation size is 0.
Fix issues related to trying to erase lengths of zero.  NB: This is basically to allow an out of range index so long as the operation size is 0.

ruleless/CEGUI,ruleless/CEGUI,OpenTechEngine/CEGUI,OpenTechEngine/CEGUI,OpenTechEngine/CEGUI,ruleless/CEGUI,ruleless/CEGUI,OpenTechEngine/CEGUI