Added functionality for drawing text and enhanced the IMG_ API

|SOURCE|
[Image]
* Removed the width and height parameters from Draw, as the entire image will
  be drawn, use DrawSub for sub-region drawing
* Added DrawSub to draw a sub-region of an image
[Text]
* DrawCharacter uses a FONT along with a position and the character to draw, in
  order to draw a character to the screen
[Font]
* Re-named CreateFont to Create as it is redundant to describe the API's intent
  twice
[Main]
* Commented-out the section for drawing a 3D polygon as the font drawing has
  taken precedence
* Added a section to display the new IMG_DrawSub function and anther section
  for drawing text, which currently only draws the character a at a
  user-defined point on the screen