0.2.0

New features:

• Progressive JPEG decoding (SOF2) with spectral selection and successive approximation
• Image#each_rgb for iterating pixels without per-pixel struct allocation
• PureJPEG::DecodeError exception class for all decoding errors
• Validation of custom quantization tables (length and value range)

Performance:

• Packed integer pixel storage in Image eliminates per-pixel object allocation on decode (~6x faster decode)
• Fast path for encoder pixel extraction from packed sources (ChunkyPNGSource, Image)
• BitReader#read_bits fast path when buffer already has enough bits
• BitWriter builds a String directly instead of Array + pack
• Huffman.build_table returns an Array for O(1) lookup instead of Hash
• Faster scan data extraction using String#index

Fixes:

• JPEG data detection uses SOI marker check instead of null-byte heuristic
• RawSource pixels default to black instead of nil
• BitReader bounds check for truncated 0xFF sequences
• JFIFReader bounds check when reading past end of data
• Fixed dead tautological check in AC encoding EOB logic