This style was unconditionally used for all multiline controls for some
reason, meaning that wxEVT_TEXT_ENTER could be received even for the controls
not using wxTE_PROCESS_ENTER explicitly, which was unexpected.
Don't do this any more to conform to the expected behaviour.
Also do use wxTE_PROCESS_ENTER for the text control supposed to allow handling
"Enter" in the text sample: surprisingly, it didn't have this style before,
although it was clearly supposed to.
Closes#1913.
fbf59742a4