Convert TypeTable::loadFromFile() to modern types.

Convert TypeTable::loadFromFile() to modern types.

The KConfig::read*Entry() functions return QStringList and QString, and
we do no longer work with char*.

A marginal change is a fix to the value of m_displayName if no
DisplayName property was set in the type table file: We use QFileInfo to
find the file name instead of doing it manually and in the wrong way by
scanning for a backslash instead of a slash.