Expand Image class capability

[RippeR37]

Implement new features, such as:

• loading multiple image file formats:
  • BMP
  • TGA
  • JPEG
  • PNG (Be aware that PNG files can have corrupted sRGB profile and this could lead to incorect behaviour of saving such images or they can be displayed incorrectly!)
• saving images to files using formats:
  • BMP
  • TGA
  • JPEG
  • PNG
• saving screenshots from applications (both at the end of rendering frame or exactly now)
  • whole-screen screenshots
  • user-defined-rectangle screenshot
• better API to work with Images
  • get/set method for accessing pixels
  • ?
• implement some algorithms to work with images such as:
  • transform to grayscale
  • invert colors
  • cropping (if cropped image is out of image's boundaries, it's move to fit with smaller size)
  • invert(flip) horizontaly/verticaly
  • rotate (90deg clock-wise, 90deg counter-clock-wise, 180deg)
  • etc.
• and maybe more

Be aware that images loaded in Image class manually (with custom loader or as copy of existing array) has to have 4-byte alignment in each row. Please refer to implementation of unsigned int Image::getAlignedRowSize(unsigned int width, unsigned int bits) method which returns size (in bytes) of aligned to 4bytes image's row. This method have public static modifier which allows you to use it in your own module based your own data to calculate proper row size.

[RippeR37]

e9f6140 commit changes:

• switched to exceptions for error handling in Images and Textures (to avoid creation of useless objects)
• implemented load(width, height, bits, data pointer) method to load image from existing array.
• changed default storage format for images and textures from BGR to RGB
• implemented swapComponents(...) static method that swaps red and blue channels in image data (BGR<->RGB swap). Used internally on BMP and TGA files.