Consolidated Texture Shader Objects

The TextureShader class now has 2 pixel shaders, allowing the use of a
second pixel shader without requiring a second TextureShader object.
Commented out the bulk of the ActiveAgent class' Search function and
added a return statement (Avoid potential infinite loop, allow code to
compile).
Mouse Click

Now check for release of the left mouse button instead of if it is
currently pressed down when checking if certain behaviours should
trigger. (state change, exiting the application - buttons)
Initial Agent Rendering

Initial agent rendering test.
Moved highlighted hex coordinate calculation to HandleInput function for
proper accessibility to the results.
Initial Agent Movement

Basic functionality for moving an agent.
Split agent rendering into new Sprite class.