Reduced the use of smart pointers in SevenZipCore.
Modified return value type of Helper::QueryInterface.
Use make_unique (C++14) instead of direct using unique_ptr.
Reduced the use of smart pointers.
Fixed a problem in ModelBase::EntryVector.

ModelBase::EntryVector cannot be vector<unique_ptr<EntryBase>> since there is an explicit copy constructor (= default) attempts to copy everything in the class (includes the unique_ptr) and causes the compilation fails.
Reduced the use of smart pointers.
Fixed uninitialized variable.