|BUILD CONFIGURATION|
[Linux]
* Linking against SDL_ttf

|SOURCE|
[Common::GUIManager]
* Added AddGUIElement to push the given element into the list of elements
* Render calls each GUIElements' Render member function in the list
[Common::GUIButton]
* Added an SDL TTF font and a text member variable
* Added SetFont to load the given font and use the point size to set it up
* Added Render from the base class to allow this element to render something
* Render resizes the rectangle surrounding the text to encompass it, which
  scales with the font size
[Common::GUIElement]
* SetSize sets the width and height of the element
* Added a pure virtual function, Render, which base classes will override with
  their own functionality
* Removed setting the w and h parameters of the m_BoundingBox when SetPosition
  is called, as the w and h are the width and height, not the x+w and y+h,
  respectively
[Common::FontCreator]
* Initialise
  * The minimum window size is set to 1024x768
  * SDL_MaximizeWindow is only called if a previous configuration file was not
    found
  * SDL's TTF_Init is called
* Cleanup calls TTF_Quit to clean up the TTF library in use
* Execute
  * Added a GUIButton for testing, which is located at offset 100, 100 with the
    font VT323 which has "TEST BUTTON" for the text
  * Pressing the F1 key will toggle rendering the GUI elements' debug overlay