modify scripts to work as setuptools 'console_scripts', where the main
function takes no arguments;
add empty identifier "" in 'packages' argument of setup, to install the
standalone sstruct.py and xmlWriter.py for legacy support;
remove py2exe since it is made redundant by setuptools 'console_scripts';
remove custom 'build_ext' command since the eexecOpmodule.c is no longer
present.