Undocumented MMSYSERR_INVALPARAM return from TextToSpeechStartupEx if dictionary is missing

[ChlorideCull]

As the title says - nothing catastrophic obviously, but isn't listed in the old documentation, so it did lead me on a wild goose chase until I figured out my build system didn't end up copying dtalk_us.dic to the right place.

Might be worth documenting when this project gets around to start updating the documentation.

[7coil]

Would always be nice to have better errors - In the meantime; my work on cmake should reduce the possibility of this happening because the build system won't be as "hard to read", and should automatically copy dtalk_us to the correct place.