v0.2.1

The following features have been implemented:

• Version number (excluding patch level) is embedded in hash so that on version upgrades the cache is regenerated. For example, 0.2.1 -> 0.2.2 will not force regeneration, but 0.2.1 -> 0.3.0 will

• Support for parentheses expansion:

  Will it (rain|pour) (today|tomorrow|)?
  

  Will turn into:

  Will it rain today?
  Will it rain tomorrow?
  Will it rain?
  Will it pour today?
  Will it pour tomorrow?
  Will it pour?