Release 2.1.0

• Fixed bug compiling every procedure twice
• Fixed implementation of procedure expt
• Fixed overflow issues in procedure approximate
• Fixed crashes in the rounding functions when used with rational big integers
• Moved procedure load into library (lispkit core)
• Integrated simple bytecode optimizer
• Implemented support for tagged procedures
• Implemented support for procedures with optional arguments
• Included new libraries: (lispkit math util), (lispkit math stats), (srfi 166), (srfi 227), and (srfi 229)
• Ported Peter Norvig's pattern matcher and algebraic simplifier from Common Lisp to Scheme and included it as new example code
• Extended sample code Math.scm