Cosmetic INI discrepancies

In ./tests, there is a unit test for the INIParser, consequently showing what is currently being preserved when reading an INI file.

Some discrepancies remain between the read INI and the one we save back out, the biggest ones being:

1. In an effort to keep them as close as possible, if the default section [General] is not specified in the input file, it will not be written out. Currently this leads to the section header not being written out if there's both keys before any section, and later the default section found.

2. Empty sections should not be written out, unless they are already present in the INI file (like it is already implemented for default keys).

effort: 1/2 day