Prefer one public class per file over monolithic files

[Nikhil-42]

Description

The m_array.py module contains definitions and implementations for several related but public classes. This drastically reduces the readability of the file. There is general refactoring required here such as making MArrayElement an internal class, and splitting MArraySlidingWindow to a different file.

[Nikhil-42]

Also, the file name should match the main class defined in that file. Ie "m_array.py" -> "marray.py" and "marrayslidingwindow.py"