Cleaned file up and fixed a bug that caused a segfault when removing items from the Array.

src/Array.cpp
  - Removed bug that caused segfault. Bug was due to a tautology as a for-loop condition.
  - Reoriganized file so definitions are inside class declaration.
Removed Entity information from App class, making it a true base class.

include/App.h
  - Removed all data using BasicEntities.
  - Moved empty declarations of render() and onMousePress() here.
  - Changed render declaration from
      void render()
    to
      void render(sf::RenderWindow *)
    to get around m_window being private and only used in render().

src/App.cpp
  - Removed all drawing and logic of circles.
  - Changed render() and onMousePress() to empty virtual functions.
  - Moved those definitions to include/App.h.
  - loop() now class clear() and display() methods of sf::RenderWindow to
    better hide the m_window from someone who extends the class.
Created directory and files for TicTacToe application.

TicTacApp/
  - Created to house all files specific to TicTacToe application

TicTacApp/main.cpp
  - Created to launch TicTacToe app

TicTacApp/TicTacApp.h
  - Extended src/App
  - Now houses Array<BasicEntity>
  - Learned more about C++ inheritance syntax

TicTacApp/TicTacApp.cpp
  - Draws 9 circles max and recycles space in array as necessary
    when drawing more circles
Updated Task List.