Throttler: Rename "framelimiter" to "emulation speed".

We don't throttle by frames, we throttle by coretiming speed.
So looking up VI for calculating the speed was just very wrong.
The new ini option is a float, 1.0f for fullspeed.
In the GUI, percentual values are used.

Source/Core/VideoCommon/VideoConfig.cpp

@@ -311,5 +311,5 @@ void VideoConfig::Save(const std::string& ini_file)
 
 bool VideoConfig::IsVSync()
 {
-	return bVSync && !Core::GetIsFramelimiterTempDisabled();
+	return bVSync && !Core::GetIsThrottlerTempDisabled();
 }