sapi5 throwing exceptions when encountering xml character

[jdude08221]

when writing text starting with <, the sapi5 returns an exception if there is not valid xml following that character.

from
https://docs.microsoft.com/en-us/previous-versions/windows/desktop/ms720892(v=vs.85)

it seems like there are some flags that can be passed to the Speak function. It might make sense to just default the Speak function flags for _tts in sapi5.py to be SVSFIsNotXML (16) as the way it is now, it basically breaks on xml

self._tts.Speak(fromUtf8(toUtf8(text)), 16)

[willwade]

See also #287