Prepare new release. (#267)

Add missing headers (#239)

Two changes:

1. Add `#include <cinttypes>` to `test/cctest/cctest.h`. Without it, on
Linux systems, the following error occurs:

```
note: 'PRId64' is defined in header '<cinttypes>'; did you forget to '#include <cinttypes>'?
```

and similarly for `PRIu64` macro. 


2. `double-conversion/bignum-dtoa.h` added as a required header in
`CMakeLists.txt`.

`double-conversion/bignum-dtoa.cc` is added to the library which
references this header.

Prepare v3.2.0 release. (#196)

Issue #184 : Fixed all -Wzero-as-null-pointer-constant warnings (#185)

Prepare for 3.2.0 release.

Update changelog and version number.

Update Changelog and version.

Fix some issues with invalid hex-float literals.

When converting `0x` the converter would assert (or access out of
    boundary).
With `0x1.p1234556666FFFFF` the converter would overflow and not yield
the correct exponent.

Switch to relative includes.

Fixes #91.

Fix typo in test.