Add overloaded operator << for OwnChar instance and pointer.
Add assign operator for OwnChar.
Make minor improvements for OwnChar.

 * default construcltor make instance with \0 character;
 * mark some methods with const modifier.
Implement assign methods for OwnChar traits.
Implement methods for comparint OwnChar by traits.
Implement copy\move methods of OwnChar traits.
Implement compare method of OwnChar traits.
Implement getting length of OwnCharString.
Implement find of OwnCharTraits.