Changes in 0.3:
  - If a nonce ends up out of date (due to an application crashing without 
    saving the current nonce(s), for example), one attempt will be made to 
    update the nonce held by the key handler and retry the call that failed.
  - Created a BTCEConnection object to make it easier to re-use a connection
    when you know you'll be making multiple requests.  Functions/methods
    that make HTTP requests now take an optional connection object; if none
    is provided one will be created automatically, so there should be minimal
    code changes required.
  - Users can set the HTTP connection timeout by providing it to the 
    BTCEConnection constructor.
  - The KeyHandler constructor resaveOnDeletion argument now defaults to True.
  - The keys attribute of a KeyHandler now returns a list of keys instead 
    of a dictionary of keys to (secret, nonce) pairs.
  - Removed the next_nonce method of the TradeAPI class, as the key handler
    should just be called directly.
  - The TradeAPI constructor arguments have changed; the key handler is now
    required and is the second argument instead of the fourth.
  - Removed old print_account_info.py sample.

Changes in 0.2:
  - There have been several API changes (detailed below), but hopefully this
    version will not break your code too much.  I've tried to stick to issuing
    warnings where breakage may occur in later versions.
  - Switched to decimal.Decimal for currency handling to avoid rounding issues.
    This is the one change that is most likely to break your code.
  - The TradeAPI now takes an optional handler, which should be a KeyHandler
    instance (or equivalent).  This allows the TradeAPI object to automatically
    update the nonce held by the KeyHandler. In future versions, this argument 
    will be required, and the secret argument will be removed, as the handler
    can provide this information.
  - The KeyHandler constructor now takes an optional resaveOnDeletion argument,
    and this class will automatically rewrite nonces back into the key file on
    deletion if this flag is true.
  - The all_currencies, all_pairs, max_digits, and min_orders variables in 
    common are now available at the top level of the library.
  - Switched all classes to be new-style (I wanted to make the KeyHandler keys
    member a property for backwards compatibility, and the property decorator
    works best with new-style classes, so this is mainly for consistency).
  - Added a new sample showing suggested 0.2 usage.  The old sample remains
    for now.
  - Changed common.formatCurrency to take a pair instead of maxdigits so you
    no longer have to do that lookup yourself.
  - Added more tests.