* Move enable_testing() into proper place
* Added CMake's checks for C++11 standards
Raised minimal version of CMake to 3.1, since on old systems there no
decent compilers that supports c++11.
Closes#377.
* Externalize googletest project
Externalize gtest to avoid installation, fixes#539.
* Remove defined cmake_policies
CMP0012 - OLD marked as deprecated for >=cmake-3.1 and will be removed
CMP0015 - does not affect to build process
CMP0042 - already NEW for >=cmake-3.1
Fixes#505
* Fix compiling in Windows MSVC
- Adds 'std=c++11' compiler flags
- Replaces boost::type_traits with std::type_traits
- Replaces boost::shared_ptr with std::shared_ptr
- Replaces std::auto_ptr with std::unique_ptr
- Replaces raw pointers with std::unique_ptr in ptr_vector, ptr_stack, and SettingChanges
- Replaces boost::noncopyable with deleted copy and assignment operators
- Replaces boost::next with std::next
- Replaces boost::enable_if with std::enable_if
- Replaces boost::is_convertible with std::is_convertible
- Replaces ptrdiff_t with std::ptrdiff_t
- Replaces boost::iterator_facade and boost::iterator_adaptor with std::iterator, borrowing the 'proxy reference' technique from boost
- Removes Boost dependency from CMakeLists
- Formats changed files using clang-format
