- Removed unneccessary variables.
- Made a function of that part of code, which actually changes 
  the line under modifications.
- Fixed memory overrun problem with my_malloc. Too little space
  was reserved.
- Fixed problem in case, when new option was added at the end
  of the section. Before, it was added as the last line of the
  section, even if it left empty lines between.
- Fixed so that the configuration file is not saved unneccessarily,
  if no modifications are done. (file timestamp remains)
- This should fix (at least partially) problems described in
  Bug#10806