v0.3.1: Auto merge of #40 - mbrubeck:docs, r=Ms2ger

• New:
  • SmallVec implements the Default trait (#30).
• Deprecated:
  • push_all_move (use extend instead)
  • type aliases (e.g. SmallVec2). Use SmallVec<A>' instead (e.g. SmallVec<[T; 2]>`)
• Removed:
  • VecLike::len (use the inherent len slice method instead) [breaking change] (#38).
• Bug fixes:
  • Fixed a memory safety hazard in grow (#40).
• Performance improvements:
  • shrink_to_fit will move data to the stack when possible (#40).
• Improved:
  • More documentation, more tests, more benchmarks, and misc. code cleanup.

There is no version 0.3.0. This version was published as 0.3.1 instead of 0.3.0 by accident.