First of all, thanks for making such a useful library available !
I noticed a minor 'feature' when trying to get the value of an optional configuration item.
For example the following:
double value = 1;
works as expected if the configuration file contains:
optionalValue = 2.0;
but does not modify the variable value if the configuration file contains:
optionalValue = 2;
(i.e. the value is recognized as int but not as double).