Cexprtk

New Features

* Support for Python 3
* Custom python functions can now be registered with `Symbol_Table` and used in expressions.

New Features

* Updated version of bundled `exprtk` to that current as of 3rd August 2017.
* Updated `cexprtk` wrapper code to be compatible with this version of `exprtk`.
* Enabled pickling of the `Expression` and `Symbol_Table` classes. Primarily this is to allow their use with the multiprocessing module.

New Features

* Allows re-use of parsed mathematical expressions through new classes:
- `Expression`
- `Symbol_Table`
* Expose support for unknown symbol resolver through the `unknown_symbol_resolver_callback` argument to the `Expression` constructor.
* Improved documentation:
- API reference.
- Examples of the new classes.
* Updated version of `exprtk` bundled in `3rdparty`

Bug-Fixes

* Modifications to allow `cexprtk` to build on windows.

Bug-Fixes

* Module would not build if cython installed.
* Now build from pre-cythonized `cexprtk.cpp` whether `cython` available or not.

* Initial Release