v0.3.2: Auto merge of #43 - mbrubeck:uninit, r=jdm

• New SmallVec methods:
  • insert_many (#28)
  • extend_from_slice and insert_from_slice (#29)
  • from_slice (#42)
  • into_vec (#45)
• Integration:
  • Optional support for the heapsize crate (#42).
• Performance improvement:
  • Don't zero memory on initialization (#43).