Overhaul implicit conversion of arguments and return values * oct-py-types.cc, oct-py-types.h (pytave::py_implicitly_convert_argument, pytave::py_implicitly_convert_return_value): New functions. * __py_struct_from_dict__.cc, oct-py-eval.cc, pycall.cc, pyeval.cc, pyexec.cc: Use them instead of legacy conversion functions. Add necessary #includes, remove #includes of legacy header files. * @pyobject/subsasgn.m, @pyobject/subsref.m: Change %!tests that depend on NumPy implicit conversion into %!xtests. * octave_to_python.cc, octave_to_python.h, python_to_octave.cc, python_to_octave.h: Delete, no longer used. * Makefile.am (COMMON_SOURCE_FILES, PYTAVE_HEADER_FILES): Remove the files.

--- a/pyexec.cc	Tue May 02 17:40:01 2017 -0700
+++ b/pyexec.cc	Wed May 03 16:30:45 2017 -0700
@@ -33,7 +33,6 @@
 #include "oct-py-eval.h"
 #include "oct-py-init.h"
 #include "oct-py-util.h"
-#include "python_to_octave.h"
 
 DEFUN_DLD (pyexec, args, nargout,
            "-*- texinfo -*-\n\