Need RegOpenKeyEx()

[rodrigc]

In Twisted, I tried to replace pywin32 with pywincffi: twisted/twisted#920

I found that the following are not in pywincffi:

win32api.RegOpenKeyEx()
win32api.RegQueryValueEx()
win32api.RegQueryValueEx()

@opalmer can you add them?

[opalmer]

@rodrigc could you use the winreg module instead?

https://docs.python.org/3/library/winreg.html#module-winreg
https://docs.python.org/2/library/_winreg.html#module-_winreg

I didn't include these functions in #69 originally because the code calling those functions had been deprecated and the standard library appeared to have the necessary support already. It also avoids a few layers of abstraction by not calling into pywincffi for these particular functions.

[rodrigc]

OK, please review this: twisted/twisted#921

[opalmer]

Thanks, reviewed. I'm going to go head and close this.