#278 Save mechanism confused between hsol and hcfg

[sid-the-sloth]

Scenario:
1. create new puzzle, solve a step
2. save the puzzle as... (.hsol)
3. save configuration as... (.hcfg)
4. make some change to the puzzle (solve a bit more)
5. save the puzzle (Ctrl+S)
6. BUG: the puzzle is now saved with the filename of the configuration file saved at step #3
7. Looks like the config file is lingering and saving the puzzle re-uses the config filename (.hcfg) instead of the puzzle filename (.hsol)