KoSectionModel passed unittest!

KoSection bounds documentation changed;
KoSectionModel::createSection childrenId lookup fixed;
KoSectionModel::sectionAtPosition fixed with new
section bounds meaning;
KoSectionUtils Added some const to params;
DeleteCommand Fixed bugs in Model and Formatting
level section handlings
TestKoTextEditor::testDeleteSectionHandling fixed
3 wrong unit-tests and changed $ in doc to P (paragraph)
symbol