v0.5.0

• Rust bindings, published on crates.io and covered in the docs
• Adds SQL helper functions for storing DNA/RNA sequences as compact BLOBs using two bits per nucleotide.
  • nucleotides_twobit()
  • twobit_dna()
  • twobit_rna()
  • twobit_length()
  • see Programming Guide for details