Implement first working version of item 8.
Add C++ Primer exercises 2-9 and 2-10.
Add C++ Primer exercise 2-18.
Add exercises 2-15, 2-16 and 2-17 from C++ Primer.
Add exercise 2-13 and 2-14 from C++ Primer.
Add exercise 2.12 from C++ Primer.
Add exercise 2.11 from C++ Primer.
Add exercise 2.10 from C++ Primer, 5th edition.
Add exercise 2.9 from the C++ Primer, 5th Edition.
Add scoped_ptr example.
Add virtual functions test.
Make code compile.
Add std::distance example.
Merge branch 'item8'

Conflicts:
	books/C++_Primer/Fifth_Edition/exercises/Chapter02/exercise2-09.cpp
	books/C++_Primer/Fifth_Edition/exercises/Chapter02/exercise2-10.cpp