New ArrayMap class.

This is a new kind of key/value mapping that stores its data
as an array, so it doesn't need to create an extra Entry object
for every mapping placed in to it.  It is also optimized to reduce
memory overhead in other ways, by keeping the base object small,
being fairly aggressive about keeping the array data structures
small, etc.

There are some unit and performance tests dropped in to some
random places; they will need to be put somewhere else once I
decided what we are going to do with this for the next release
(for example if we make it public the unit tests should go in
to CTS).

Switch IntentResolver to using ArrayMap instead of HashMap.

Also get rid of a bunch of duplicate implementations of binarySearch,
and add an optimization to the various sparse arrays where you can
supply an explicit 0 capacity to prevent it from doing an initial
array allocation; use this new optimization in a few places where it
makes sense.

Change-Id: I01ef2764680f8ae49938e2a2ed40dc01606a056b