[X10-core] rippling conversions from int to long in X10 2.4

[David P G. <gr...@us...>]

For X10 2.4, we've made the jump to long-based indexing for Rail, Point,
Region, Array, DistArray, etc. This enables X10 2.4 to naturally support
very large array-based data structures (both single place and distributed).

A natural corollary of that is that x10.util.ArrayList should probably also
be upgraded to long-based indexing (since one is supposed to think of
ArrayList as a "collectionized" GrowableRail, and Rail/GrowableRail are
indexed by longs).

In itself, that change makes sense, but it then pushes into the rest of the
x10.util collection APIs.  In particular, the indexing methods of ArrayList
are implementations of the List interface.  Furthermore, the size method of
ArrayList implements the size method of Container.   Should we follow
through the change to the logical conclusion and make all of the x10.util
collections 64-bit sized?

One the one hand it seems like the most consistent thing to do.  On the
other hand, it cause more API incompatibilities with X10 2.3.x and isn't
quite as obvious that having the size of Maps and other collections be 64
bit is quite as useful as it is for array-like data structures.

Any thoughts?   I think I'd lean to making everything 64-bit in the name of
consistency, but I don't think we absolutely have to.

thanks,

--dave