Fixed cIniFile's SetValue().

How did we not see this earlier? Each call to SetValue would actually ADD a value!
Merge branch 'master' into IniFileFix
IniFile: Split SetValue() into AddValue() and SetValue().

Each function does what one would assume - AddValue adds a new value, SetValue overwrites existing value (creates a new one if not exists, if instructed to do so).
Documented the cIniFile:AddValue* functions.

Now the documentation really matches the implementation.
Fixed reading the files.

Duplicate values were ignored.
Merge pull request #526 from mc-server/IniFileFix

Fixed cIniFile's SetValue().