Shed Skin 0.0.18

yes, it's the fourth release of shed skin in about a month. can you tell I'm working on it full-time now? :) here's a list of major changes:

-modifications to work on OSX and 64-bit systems
-improved support for class attributes
-classes can now be used prior to their definition
-several optimizations and fixes for strings
-hash value caching for strings and tuple{int,double,str}
-optional bounds checking using --bounds

thanks to jplevyak, larry, gustavo and denis for helping to get SS to work on 64-bit and OSX systems!

note that it's very hard for CPython to cache hash values for tuples (because the elements might be mutable). once types are known however, e.g., for tuple, SS can cache hash values no problem. this can cause quite a speedup.. for example, the following program is now 10 times faster than under CPython (corresponding to the 10 loop iterations):

sign_words = {}
kawamabahana = 10000000*(1,2)
for x in range(10):
hash(kawamabahana)

I'm going to take a few days off now, and think about a strategy to add iterators (and hence generators and generator expressions), and possibly non-uniform tuples of length greater than 2..