Locale fix

Fixed some problem we had when loading files made with one system locale on systems with other locale settings.
Modified the serialization and deserialization for interpreters, also fixed the property grid.

Now the default behavior is the following:
- the info is saved and loaded from file with CultureInfo.InvariantCulture,
- on the property grid the system locale is used. On US a decimal is like 12.38 on DE the decimal is 12,38.