Improve user config input using .ini file

Main changes:
- Configuration variables are read from .ini file to a struct
- Added function extractStructFields to set variables from fields (be careful with renaming)
- Modified readConfigFile: now it literally assigns values in .ini to fields
- Improved data set path reading: It is automated from previous path and datasetname variable and user input by uigetdir is only requested when no folder is found
- Output for loadDataset is a struct