v0.2.0

• New: Elo.setUserIdentifier ties ad requests to your own user account.
  Every request carries an anonymous, per-install visitor_id the SDK
  generates. Apps with a sign-in can now supply their own identifier instead,
  and it replaces that anonymous id on subsequent ad requests and their
  tracking pings — so delivery, frequency capping, and reporting follow the
  user across installs and devices rather than the install. Call it once the
  user is known and clear it on sign-out; the order relative to Elo.configure
  does not matter. The anonymous id is kept underneath, so clearing restores
  the same one the install had before. An ad keeps whichever identity it was
  requested under for its whole lifetime, so an impression that fires after a
  sign-out is still reported against the request that fetched it. The
  identifier lives in memory only (re-set it on each launch) and is cleared by
  shutdown(); a re-configure does not clear it, since a config refresh is not
  a sign-out. Whitespace is trimmed, a blank string clears it, and values over
  256 characters are ignored with a warning.

• Fix: a scrolling ad description now scrolls a few times and then settles,
  instead of scrolling for as long as the ad is on screen. A permanently
  animating line keeps the host app's UI from ever going idle, which stalls
  automation frameworks that wait for idle before each interaction and keeps a
  frame in flight for no reason. The description now makes three passes — the
  same budget as iOS — then stays tail-ellipsized like any other line. Scroll
  speed, the holds at each end, travel distance and row height are unchanged,
  and a new creative gets its own passes.

• Fix: the loading placeholder's shimmer now sweeps a few times and then
  rests, and stays still for anyone who has turned animations off. It
  previously repeated for as long as the placeholder was on screen, with the
  same never-goes-idle consequence, and a request that hangs holds the
  placeholder there indefinitely. It now shimmers well past the point a normal
  ad request returns, then rests as a plain skeleton.

• Fix: creatives whose image is a .ico now show their thumbnail.
  Publishers commonly supply a site favicon as a creative image, and favicons
  are often ICO — a format Android cannot decode, unlike iOS. The image load
  failed and the ad rendered with no thumbnail at all, so the same creative
  looked different on the two platforms. The SDK's image loader now decodes
  ICO itself (both the PNG-embedded and the uncompressed-DIB forms, picking
  the largest image in the file), closing the parity gap.

• A creative image that fails to load now logs a warning. The thumbnail
  drops out silently by design, which made an unreachable or undecodable image
  host indistinguishable from a creative that simply has no image. The failing
  URL and cause are now logged at warn level under the Elo tag.

• Fix: a creative that wins more than once now records a render and an
  impression every time it's shown. Render and impression dedup was keyed on
  the creative id, which is stable across ad requests — so the second and every
  later time the same creative won an auction in a single app session, the SDK
  suppressed both pings while the ad still displayed and still clicked.
  Those ad opportunities reached the server as a click with no render and no
  impression behind it. Dedup is now keyed on the ad opportunity, so repeated
  showings of one creative each report their own render and impression, while
  the guarantee that matters is unchanged: recomposition, scrolling an ad out
  of a lazy list and back, or a configuration change still reports exactly one
  render and one impression per opportunity.

  Expect reported renders and impressions to rise once this ships — the
  missing events were never counted. Click volume is unaffected. Publishers
  whose reporting showed clicks exceeding impressions for a placement should
  see that resolve.

  One consequence worth knowing: Elo.shutdown() now clears render dedup state
  as well as impression state, so an ad shown before shutdown can report again
  after a re-configure.