0.5 Draft Release

• Fixes various issues with semantics #7
• Adds new example
• Adds url to SICP
• Removes thunk definition since not used #5
  Thanks go to @omasanori and @Zipheir

0.4 Draft Release

Various minor changes including:

• Adding pair notation for datum: (a . b)
• Explicitly stating that Pico Scheme implementations may bind to values.
• Switching empty list to mainindex.
• Removing named let from tail recursion since named let not in spec.
• Removing mention of multiple return values in tail recursion section.
• Since Pico Scheme does not have side effects, adding note that order of
  evaluation is irrelevent.
• Clarifying that Shinn, Cowan, and Gleckler are R7RS, not pico scheme
  editors.
• Noting that let and apply are optional.
• Removing convention for non-negative integer since it is unused.
• Misc copyediting fixes.

0.3 Draft Release

This switches the name to Pico Scheme since there already was a Tiny Scheme implementation.

0.2 Draft Release

Fixes various issues in version 0.1

0.1 Draft Release

This is the first draft release.