Subtitles: Remove extraneous character in embedded text subtitles.

The NUL character at the end of the C string was accidentally being
included as part of the subtitle string, and rendered to the screen.
This affected only "raw text" subtitles directly embedded into the
video.  Fixes #11855.
(cherry picked from commit b062dd43ba26836c854a0c8fda845f9997b8fba9)
Mythweb: Prevent unnecessary 30-second delay after rescheduling.

For the listenForEvent() method, manually close and reopen the backend
connection in a way that allows MythEvent messages to be received.

Fixes #11853.
(cherry picked from commit fdf205485bf65ce4feb2d233da600e37aad8b0fc)