In the HTML doc, following items are added
* Changes in 3.3.1
* Update input domain of trigonometric functions

Changes in 3.3.1 is added to CHANGELOG.md

This patch adds a modified Payne Hanek argument reduction that can be used for very large arguments.

Payne Hanek reduction algorithm can handle very large arguments by table look-ups. In this patch, a vectorized version of the algorithm is implemented. The argument range for DP and SP trig functions will become [-1e+299, 1e+299] and [-1e+28, 1e+28], respectively. In order to avoid using 64 bit or 128 bit multiplication, the algorithm is modified to use DD computation. Gather instructions are used for table look-ups. The reduction subroutine is tested to confirm that it correctly handle the worst case with 6381956970095103.0 * 2.0^797.

This patch adds support for POWER VSX.
clang-5.0 and later is supported at this time.
gcc-8 should be able to compile the VSX code, but I haven't checked.

This patch adds 3.5-ULP versions of sinh, cosh, tanh, sinhf, coshf, and tanhf. Corresponding testing functionalities are also added.
This patch adds the corresponding functions to the GNUABI version of library.

This patch adds SVE support to the DFT library.

The DFT library strongly depends on the vector length, and thus it does not mix well with vector-length agnosticism. In this patch, the utilized vector length can be specified by CONFIG macro in helpersve.h. The DFT subroutine uses a dispatcher to choose the kernel subroutine from those compiled for 2048, 1024, 512 and 256-bit vector lengths.

* CHANGELOG.md is updated according to the changes made.
* An error will be generated if VECTLENDP or VECTLENSP are redefined at helpersve.h
* Added explanation of the meaning of VECTLENDP and VECTLENSP to helpersve.h.

This is the merge commit of the development branch `cmake-transition`.

This changes makes sure that:

1. `liblseef`, `libsleefgnuabi`, and `libdft` are build with the Makefile system;
2. tests for `libdft` are executed with the Makefile system;
3. `libsleef` and `libsleefgnuabi` are built and tested with cmake.

Notes:
1. `libdft` is build on linux only for gcc.
2. The makefile build of `libsleef` is done only for linux/gcc.
3. The `ENABLE_WEAK_ALIASES` C macro has been replaced with
    `ENABLE_GNUABI` to handle with the same maro both cmake
    and Makefile build systems.
4. A change log file has been added. This will be used to keep track
    of the changes. It uses the format specified in
    http://keepachangelog.com/en/1.0.0/

5. The macro `ENABLE_GNUABI` is set up as a consequence of the
    configure time check `COMPILER_SUPPORTS_WEAK_ALIASES`.
    The `SLEEF_ENABLE_GNUABI` cmake variable has been replaced
    with `ENABLE_GNUABI`.