sparkup.py: re-add python2 shebang line, chmod +x

Ref: #72 (this fix was lost)
Makefile: use sparkup.py as source (changed recently)

TODO: should use a build dir; `generic` might not exist
Remove `--filetype` option; Vim: pass `--xml` properly

vim/ftplugin/html/sparkup.vim:
 - pass `--xml`, if 'xml' is used in &filetype (might be several)
 - build args to sparkup on every call: its input is dynamic,
   especially the new &expandtab
 - use "python" workaround only for Windows (it is executable for
   Linux/Unix), and its shebang should be used

Fixes #69, #83.
Add support for `smarty` filetype (PHP template language)

Ref: #84
sparkup.py: remove unused code, indent/format XmlDialect
sparkup.py: fix typo in code: s/attribues/attributes/