Add method for getting section template

In In-Portal 5.2.0 "use_section" parameter of m_Link tag was introduced.
It allows to pass template filename into m_Link tag and get back nice url from "Structure & Data" section. For example:

• without: <inp2:m_Link template="in-link/my_account/my_favourites"/>; result: http://www.website.tld/in-link/my_account/my_favourites.html
• with: <inp2:m_Link template="in-link/my_account/my_favourites" use_section="1"/>; result: http://www.website.tld/in-link/my-account/my-favourites.html

I've extracted code used to process "use_section" parameter in new kApplication::getSectionTemplate method.