Rethink portable releases:

* Remove complicated and unreadable NSIS stuff. No need to have a installer for a developer application. ZIP file is fine.
* On startup, if a portable_settings.txt exists in the application folder, heidisql.exe will read its contents into a unique registry key.
* In MainForm.OnDestroy, settings are written to that file again, and the reg key gets deleted.
* Avoid using Microsoft's .reg file syntax, as you need admin privileges to store and restore such files, even when using the appropriate Windows API functions.

source/main.pas

@@ -1176,6 +1176,8 @@ begin
     deletefile(filename+'bmp');
   if MainReg <> nil then begin
     MainReg.CloseKey;
+    // Export settings into textfile in portable mode.
+    HandlePortableSettings(False);
     MainReg.Free;
   end;
 end;