Support more architectures.

Patch from Mike Homney (Mozilla Foundation).
Null terminate exponent buffer.

Fixes issue 26.
Update Changelog.
Add ARM 64 support.

BUG: 33.
Add OsX ppc compilation support.
Rewrite tests.

Also disable a test that was triggering a compiler bug in Visual
Studio 2012. The disabled tests were only sanity checks and weren't
testing the double-conversion library.

Conflicts:
	test/cctest/test-bignum-dtoa.cc
	test/cctest/test-fast-dtoa.cc
	test/cctest/test-strtod.cc
Fix type.
Missed more int/bool types.

Conflicts:
	test/cctest/test-fast-dtoa.cc
Make checks dependent on compiler.

Conflicts:
	test/cctest/test-strtod.cc
Fix GCC's unused typedef warning.

Thanks to Chris Bracken.
BUG=37
Fix bad merge.
Fix clang warning for unused variables (only used in ASSERT).

BUG=41
Update Changelog.
Fix build on ARMv8 64bit.

I previously used the wrong variable (_ARCH64EL_ instead of
__ARCH64EL__).

BUG=33
Fix warnings.
Update Changelog.
fix bad merge.
Backport most of the SConstruct improvements.

Contrary to v2.0, v1.1 we don't have shared libraries for v1.1.
Update changelog.
Enable shared libraries in v1.1 branch.