Merged synthLanguageSupport. For most synths this provides a read-only language prope...

Merged synthLanguageSupport. For most synths this provides a read-only language property, which allows  other code in NVDA to find out the language the synth is currently speaking in. It also standardizes support for setting and listing languages by adding needed types to synthDriverHandler. The addition of the language property will allow NVDA in future to improve its puncutation handling by using appropriate rules according to the synth's current language, rather than simply either a default set of rules or rules based on NVDA's interface language.