Memory allocations are now done through smalloc. The Buffer cc class has
been removed completely, but for backwards compatibility have left the
namespace as Buffer.

The .parent attribute is only set if the Buffer is a slice of an
allocation. Which is then set to the alloc object (not a Buffer).

The .offset attribute is now a ReadOnly set to 0, for backwards
compatibility. I'd like to remove it in the future (pre v1.0).

A few alterations have been made to how arguments are either coerced or
thrown. All primitives will now be coerced to their respective values,
and (most) all out of range index requests will throw.

The indexes that are coerced were left for backwards compatibility. For
example: Buffer slice operates more like Array slice, and coerces
instead of throwing out of range indexes. This may change in the future.

The reason for wanting to throw for out of range indexes is because
giving js access to raw memory has high potential risk. To mitigate that
it's easier to make sure the developer is always quickly alerted to the
fact that their code is attempting to access beyond memory bounds.

Because SlowBuffer will be deprecated, and simply returns a new Buffer
instance, all tests on SlowBuffer have been removed.

Heapdumps will now show usage under "smalloc" instead of "Buffer".

ParseArrayIndex was added to node_internals to support proper uint
argument checking/coercion for external array data indexes.

SlabAllocator had to be updated since handle_ no longer exists.

A llvm/clang bug on Darwin ia32 makes these tests fail 100% of
the time.  Since no one really seems to mind overly much, and we
can't reasonably fix this in node anyway, just accept both types
of NaN for now.

Improvements:
* floating point operations are approx 4x's faster
* Now write quiet NaN's
* all read/write on floating point now done in C, so no more need for
  lib/buffer_ieee754.js
* float values have more accurate min/max value checks
* add additional benchmarks for buffers read/write
* created benchmark/_bench_timer.js which is a simple library that
  can be included into any benchmark and provides an intelligent tracker
  for sync and async tests
* add benchmarks for DataView set methods
* add checks and tests to make sure offset is greater than 0

to writeDoubleBE(), writeDoubleLE(), writeFloatBE() and writeFloatLE().
Fixes #3934.

Fixes #2138.

Fixes #1831