Adding user doc section and core files for new site

site/user/special/lua.md

+Skia Lua Bindings
+=================
+
+**Warning: The following has only been tested on Linux, but it will likely
+work for any Unix.**
+
+Prerequisites
+-------------
+
+This assumes one already has Skia building normally. If not, refer to the
+quick start guides. In addition to that, you will need Lua 5.2 installed on
+your system in order to use the bindings.
+
+Building lua requires the readline development library. If missing this can be installed (on Ubuntu) by executing:
+
+  * `apt-cache search libreadline` to see the available libreadline libraries
+  * `sudo apt-get install libreadline6 libreadline6-dev` to actually install the libraries
+
+Build
+-----
+
+The build process starts the same way as described in the quick starts, but
+before using gyp or make, do this instead:
+
+    $ export GYP_DEFINES="skia_shared_lib=1"
+    $ make tools
+
+This tells Skia to build as a shared library, which enables a build of another shared library called 'skia.so' that exposes Skia bindings to Lua.
+
+Try It Out
+----------
+
+Once the build is complete, use the same terminal:
+
+    $ cd out/Debug/
+    $ lua
+
+    Lua 5.2.0  Copyright (C) 1994-2011 Lua.org, PUC-Rio
+    > require 'skia'
+    > paint = Sk.newPaint()
+    > paint:setColor{a=1, r=1, g=0, b=0}
+    > doc = Sk.newDocumentPDF('test.pdf')
+    > canvas = doc:beginPage(72*8.5, 72*11)
+    > canvas:drawText('Hello Lua', 300, 300, paint)
+    > doc:close()
+
+The key part to loading the bindings is `require 'skia'` which tells lua to look
+for 'skia.so' in the current directory (among many others) and provides the
+bindings. 'skia.so' in turn will load 'libskia.so' from the current directory or
+in our case the lib.target directory. 'libskia.so' is what contains the native
+skia code. The script shown above uses skia to draw Hello Lua in red text onto
+a pdf that will be outputted into the current folder as 'test.pdf'. Go ahead and
+open 'test.pdf' to confirm that everything is working.
+