GetOptions - when default section, get only once
Added choice to include default

- Added includedefault argument to GetOptions. If true the [default]
section options are included when getting all sections.
Changed read to use buf.ReadLine()

- Changed read to use buf.ReadLine(). Before, if a configuration line
(an option) did not end with newline (\n, last line of the file without
a newline) the line was not read into the config.