MtVec: implement STL compatability

[comments]
    - Added iterator, begin(), end() functions
    - Added test for iterator and stl algorithms support

Signed-off-by: Nikola Georgiev <georgiev.nikito@gmail.com>
MtVec: Added as_string() functionality

Signed-off-by: Nikola Georgiev <georgiev.nikito@gmail.com>

	MtVec_Test.dSYM/