Style-specific API extensions

[AnonymouX47]

• Improves style-specific error handling:
  • Fixes handling of style-specific errors for subclasses defined outside the package.
  • Adds BaseImageError, GraphicsImageError, TextImageError in .exceptions.
  • Adds .exceptions._style_error() for selection of style-specific exceptions.
• Implements support for style-specific parameters.
  • Adds _style_args and _check_style_args() to BaseImage.
• Implements support for style-specific format specification.
  • Adds BasImage._check_syle_format_spec().