get_value_from_str
Description:
Creates a new GValue which represents the str value given as argument.
This is the opposite of the function get_str_from_value . The type argument is used to determine the real data type requested for the returned value.
If the str string is null, then the returned GValue is of type GDA_TYPE_NULL; if the str
       string does not correspond to a valid string for the requested type, then null is returned.
Note: the str string must be in the current locale representation
Parameters:
| this | 
           an object which implements the DataHandler interface  | 
      
| str | 
           a string or null  | 
      
| type | 
           a GType  | 
      
Returns:
| 
           the new Value or null on error  |