Add resize! method to typed arrays.

This does something that I'm not 100% sure about by modifying the data
member of an RData, but I don't see any reason to believe it's not a
reasonable course of action if the underlying pointer changes, provided
the object is fundamentally the same.

At any rate, this is just a simple realloc (well, REALLOC_N, which isn't
specifically realloc, but you know what I mean). New elements of an
array may be garbage.
Swap use of int for size_t when referring to indices or lengths.

This just seems like a Good Thing to do since it's pretty much the best
use of size_t. Leaving in the checks for less than zero for now, though,
as it'll be optimized out and if I need to change it back later, the
bounds checking is still there.
Account for loss of cache when calling ___Array#resize!

I might also add some sort of call to cached objects to allow them to
update their pointers, but for now, this will do.

I should probably move the caching code and such to C, but being able to
handle it in Ruby is fairly convenient. I'd prefer to only drop down to
C for things that would be called fairly often, and resizing a typed
array shouldn't be one of those things.
Add optimization flags.

fast-math and strict-aliasing are both disabled despite use of -O3.
Although fast-math isn't specified by -O3, I do want to make sure it's
completely disabled so that the operations are IEEE-compliant, or as
compliant as I can hope for. This comes at the cost of some performance,
but it results in somewhat-more-deterministic floating point values, so
I think it's a good trade-off. I'm not sure if this will actually have
much effect on Windows, but then this code isn't tested on Windows and
that makes it hard to say what'll happen.

strict-aliasing is disabled because it just plain breaks code in weird,
hard to debug ways, and I don't want to go through that when it's not
entirely necessary.
Clean up the readme a bit.

Just adds spacing between things and changes the indentation a bit.
Add extra files in gemspec.
Version 1.1.0