Constructor. Sets the default (hard-coded) values first, and then overwrites those with any values found in the given properties.

Constructor.

1. Sets the default (hard-coded) values.
2. Overwrites those with any values from systemDefault/gfcpp.properties
3. Overwrites those with any values from the given file (if it exists) or the local ./gfcpp.properties (if the given file does not exist).
4. Overwrites those with any values found in the given properties.