Finalize styleguide (#396)

* Add styleguide

* Encourage full luadoc

* @param and @return in code blocks

* Add multi-line table comma rule

docs/STYLEGUIDE.md

@@ -0,0 +1,65 @@
+
+# RedMew style guide
+
+Not strictly enforced, but we appreciate if you try to remain consistent with our standards.
+
+* Include at least a brief one-line summary in a LuaDoc (a comment with 3 dashes `---`) before each public-facing function
+
+* A LuaDoc with extended summary, `@params`, and `@return` is encouraged. ([LuaDoc Manual][1])
+
+* Tabs are 4 spaces
+
+* Keep each line of code to a readable length. Under 140 characters when reasonable.
+
+* Never leave trailing whitespace.
+
+* End each file with a newline.
+
+* Newlines are unix `\n`
+
+* Strings should normally be encased in `'` single-quotes. For strings with single quotes inside them, `"` double-quotes can be used.
+
+* Use spaces around operators, after commas, colons, and semicolons.
+
+```lua
+sum = 1 + 2
+a, b = 1, 2
+if 1 < 2 then
+    game.print("Hi")
+end
+```
+
+* No spaces after `(`, `[`, `{` or before `]`, `)`, `}`.
+
+```lua
+table = {1, 2, 3}
+table[1]
+```
+
+* Use empty lines between `functions` and to break up functions into logical paragraphs.
+
+```lua
+local function some_function()
+    local data = global.data
+    local format = global.string_format
+    local string = Utils.manipulate(data, format)
+
+    game.print(string)
+end
+
+local function say_hello()
+    game.print("Hello")
+end
+```
+
+* When creating a table over multiple lines, include a trailing comma after the last item.
+
+```lua
+myTable ={
+    'item1',
+    'item2',
+    'item3',
+}
+```
+
+[1]:[http://keplerproject.github.io/luadoc/manual.htm]