Create a top-level "third_party" directory

This directory now contains third_party software that is vendored into
the Servo source tree. The idea is that it would eventually hold
webrender and other crates from mozilla-central as well with a standard
patch management approach for each.

third_party/ply/setup.py

@@ -0,0 +1,31 @@
+try:
+    from setuptools import setup
+except ImportError:
+    from distutils.core import setup
+
+setup(name = "ply",
+            description="Python Lex & Yacc",
+            long_description = """
+PLY is yet another implementation of lex and yacc for Python. Some notable
+features include the fact that its implemented entirely in Python and it
+uses LALR(1) parsing which is efficient and well suited for larger grammars.
+
+PLY provides most of the standard lex/yacc features including support for empty 
+productions, precedence rules, error recovery, and support for ambiguous grammars. 
+
+PLY is extremely easy to use and provides very extensive error checking. 
+It is compatible with both Python 2 and Python 3.
+""",
+            license="""BSD""",
+            version = "3.10",
+            author = "David Beazley",
+            author_email = "dave@dabeaz.com",
+            maintainer = "David Beazley",
+            maintainer_email = "dave@dabeaz.com",
+            url = "http://www.dabeaz.com/ply/",
+            packages = ['ply'],
+            classifiers = [
+              'Programming Language :: Python :: 3',
+              'Programming Language :: Python :: 2',
+              ]
+            )