Remove the init method and move its content to the constructor.

Using the init method outside of the constructor will lead to a memory
leak, because the 2 pointers will not be deleted.

As the method is not required, I dropped it.
Remove useless checks
Merge pull request #11 from MiLk/fixes/init

Remove the init method and move its content to the constructor.
Fix typo.
Merge pull request #13 from tokutake/develop

Fix typo.
Merge branch 'develop' into features/cmake
Merge branch 'features/cmake' of github.com:MiLk/mage-sdk-cpp into features/cmake