Doxygen comments updated in Summary related classes

* Applied good practice to variable args functions (according to
  the Doxygen and phpDocumentor documentations).
* Fixed types, e.g. object[] for arrays the usually contain strings.
* Break long lines.
* Descriptions start uppercase (easier to read, even if it's not a
  full sentence).

Change-Id: I3b35d1d7313d6f0e1b8e763bd03c0e8c21038c3f
Merge "Doxygen comments updated in Summary related classes"