Update to 3.2.1

Changelog:
[v3.2.1][] - 2017-08-17
-----------------------

### Fixes
* Issue #101: Bump ABI major number due to incompatible change in struct
  when adding option annotation/comments in [v.3.1][]: `1.1.0 -> 2.0.0`

[v3.2][] - 2017-06-03
---------------------

### Fixes
* Issue #96: Add Windows/mingw compatible `fmemopen()` replacement
* Issue #98: Fix v3.1 regression, segfault on comment-only lines

[v3.1][] - 2017-05-24
---------------------

### Changes
* Refactored `CFGF_IGNORE_UNKNOWN` support, libConfuse now properly
  ignores any type and sub-section without the need for declaring an
  `__unknown` option.  When the flag is set all unknown options,
  including unknown sub-sections with, in turn, unknown options, are
  now fully ignored
* Issue #69: New API for creating titled sections at runtime,
  by Jonas Johansson @jonasj76
* Issue #92: Support for option annotation/comments.  Every option can
  now have a comment, which is both read and written from/to file.
  Disabled by default, enable with `CFGF_COMMENTS` flag in `cfg_init()`
* ABI bump: 1.0.0 --> 1.1.0, due to new functionality

### Fixes
* Build unit tests statically for easier debugging
* Issue #21: Major refactor of lexer to fix memory leaks, `cfg_free()`
  now properly releases all memory.  By Joachim Nilsson @troglobit
* Issue #64: Fixed MSVC build errors, by George Koskeridis @Gikoskos
* Issue #65: SIGSEGV when parsed default values are used with include,
  by Dmitri Zhabinski
* Issue #71: Fix syntax in rpm spec file, for CentOS/RHEL7
* Issue #73: Adjust gettext version requirement to build on CentOS/RHEL7.
  GNU gettext v0.18.2.1 update `AM_GNU_GETTEXT()` to use AC_PROG_MKDIR_P
  instead of `AM_PROG_MKDIR_P`, but v0.18.1.1 is included in Ubuntu 12.04
  LTS.  Fortunately Ubuntu 14.04 LTS ships v0.18.3.1 and Debian Jessie
  ships v0.19.3.  Unfortunately, CentOS7 and RHEL7 ships v0.18.2.1, so
  for best compat. level at this point in time we require v0.18.2.
* Issue #74: Fix typos in documentation, by Luca Ceresoli
* Issue #79: Add `fmemopen()` compat for *BSD, including macOS


(ryoon)