* version 0.7.0
  - throw+: specify message as fmt & args rather than a single string
    - can use % in args (at any depth) to represent the thrown object
  - support: move small helper functions into letfns
* version 0.7.1
  - throw+: fix so that the thrown object is only eval'd once
* version 0.7.2
  - throw+: introduce &thrown-object to allow both single-evaluation
    of object and deep substitution of % simultaneously
* version 0.8.0
  - breaking change: slingshot.core -> slingshot.slingshot
  - remove &thrown-object in favor of a gensym. (the user will never
    need to refer to it)
  - simplify/clarify support functions
* version 0.9.0
  - retire :wrapper and move :throwable to the context proper
  - stop using metadata on the context
  - provide an example in README.md
  - doc string fixes
  - change so catch hook always runs even when there are no catch
    clauses
  - provide slingshot/get-thrown-object to retrieve the object
    thrown by throw or throw+ given a Throwable caught within an
    ordinary try form.
* version 0.10.0
  - add get-throw-context and reimplement get-thrown-object using it
    - get-thrown-object will now find stones in cause chains like
      try+/catch does
    - clients looking for a uniform map-based interface to reading
      the object, message, cause, and stack traces of objects thrown
      by throw or throw+ now have it
  - shortened default message to "throw+: %s"
  - reorganize support namespace: context section
  - remove references to Stone in docs, replace with wrapper
  - slingshot.Stone -> slingshot.ExceptionInfo
    - named after similar new class in clojure.lang in 1.4
  - no longer redundantly stores message, cause, and stack-trace in
    the payload of ExceptionInfo--now stored only in the like-named
    member variables
  - reduced reflection warnings
  - doc update including moving description of throw context to
    get-throw context
  - provide the immediate object wrapper at :wrapper in the context
    (accessible via get-throw-context or in &throw-context)
  - use clojure.core's ex-data and ex-info if available, but don't
    depend on them
* version 0.10.1
  - fix slingshot version in examples to match release
  - remove reflection warnings from tests and turn on checking in
    project.clj [resolves issue 18]
* version 0.10.2
  - accept a simple string as a message for throw+ (issue 19)
  - for catch, only interpret a form as a selector if it contains a %
    symbol, allows function literals for predicates (issue 20)
* version 0.10.3
  - make exception class available from support and add clojure.test
    support for testing that the proper exception is thrown (issue 21)
  - remove replace-all and % substitution in source in favor of using
    let to bind % (issue 22)
  - key-value pair -> key-values, generalize key-value selector to
    allow any even number of items in the vector (issue 23)
* version 0.11.0
  - add :else option for try+ (issue 34)
  - improve catch by class to avoid reflection (issue 37)
  - dropped custom ex-info, ex-data, ex-class and other support for
    Clojure 1.3.0
  - modernized project.clj
  - signed artifacts for clojars
* version 0.12.0
  - new optional argument to throw+ allows specifying a Throwable as
    the cause explicitly
    - explicit cause overrides the captured cause in a catch
    - issue 29
  - now treats all IExceptionInfo objects as data wrappers
    - catch selectors refer to the map passed in to `ex-info`
    - issue 35
  - no longer provides :environment in &throw-context
    - now compatible with locals clearing
    - issue 36
* version 0.12.1
  - internal improvements
  - documentation updates for correctness, clarity
* version 0.12.2
  - improved interop with ex-info/ex-data
  - throw+ explicit cause can be nil
  - tests for more throw+ arguments
  - started travis-ci builds