DOC: Remove orphaned rst page.

`docs/src/userguide/welcome.rst` is not referenced *anywhere* in the docs.
It also seems to be superseded by `docs/src/quickstart/overview.rst`

docs/welcome.rst

-.. highlight:: cython
-
-.. _overview:
-
-********
-Welcome!
-********
-
-===============
-What is Cython?
-===============
-
-Cython is a programming language based on Python
-with extra syntax to provide static type declarations.
-
-================
-What Does It Do?
-================
-
-It takes advantage of the benefits of Python while allowing one to achieve the speed of C.
-
-============================
-How Exactly Does It Do That?
-============================
-
-The source code gets translated into optimized C/C++
-code and compiled as Python extension modules.
-
-This allows for both very fast program execution and tight
-integration with external C libraries, while keeping
-up the high *programmer productivity* for which the
-Python language is well known.
-
-=============
-Tell Me More!
-=============
-
-The Python language is well known.
-
-The primary Python execution environment is commonly referred to as CPython, as it is written in
-C. Other major implementations use:
-
-:Java: Jython [#Jython]_
-:C#: IronPython [#IronPython]_)
-:Python itself: PyPy [#PyPy]_
-
-Written in C, CPython has been
-conducive to wrapping many external libraries that interface through the C language. It has, however, remained non trivial to write the necessary glue code in
-C, especially for programmers who are more fluent in a
-high-level language like Python than in a do-it-yourself
-language like C.
-
-Originally based on the well-known Pyrex [#Pyrex]_, the
-Cython project has approached this problem by means
-of a source code compiler that translates Python code
-to equivalent C code. This code is executed within the
-CPython runtime environment, but at the speed of
-compiled C and with the ability to call directly into C
-libraries.
-
-At the same time, it keeps the original interface of the Python source code, which makes it directly
-usable from Python code. These two-fold characteristics enable Cython’s two major use cases:
-
-#. Extending the CPython interpreter with fast binary modules, and
-#. Interfacing Python code with external C libraries.
-
-While Cython can compile (most) regular Python
-code, the generated C code usually gains major (and
-sometime impressive) speed improvements from optional static type declarations for both Python and
-C types. These allow Cython to assign C semantics to
-parts of the code, and to translate them into very efficient C code.
-
-Type declarations can therefore be used
-for two purposes:
-
-#. For moving code sections from dynamic Python semantics into static-and-fast C semantics, but also for..
-#. Directly manipulating types defined in external libraries. Cython thus merges the two worlds into a very broadly applicable programming language.
-
-==================
-Where Do I Get It?
-==================
-
-Well.. at `cython.org <http://cython.org>`_.. of course!
-
-======================
-How Do I Report a Bug?
-======================
-
-=================================
-I Want To Make A Feature Request!
-=================================
-
-============================================
-Is There a Mail List? How Do I Contact You?
-============================================
-
-
-
-.. rubric:: Footnotes
-
-.. [#Jython] **Jython:** \J. Huginin, B. Warsaw, F. Bock, et al., Jython: Python for the Java platform, http://www.jython.org
-
-.. [#IronPython] **IronPython:** Jim Hugunin et al., http://www.codeplex.com/IronPython.
-
-
-.. [#PyPy] **PyPy:** The PyPy Group, PyPy: a Python implementation written in Python, http://pypy.org
-
-.. [#Pyrex] **Pyrex:** G. Ewing, Pyrex: C-Extensions for Python, http://www.cosc.canterbury.ac.nz/greg.ewing/python/Pyrex/
-
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