Culture invariant double parsing

This pull request is to fix defect [MAGN-4256 CBN not being parsed as a culturally invariant string] (http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-4256#)

It is because we use Double.TryParse() to parse a string to get double value, but this function by default uses current culture to parse double. Change it to use invariant culture.