Add contribution guide.

CONTRIBUTING.md

@@ -0,0 +1,43 @@
+# Coding Guidelines
+
+## C++ Coding Guidelines
+
+### Indenting and Spacing
+
+- Indenting must be done with tab characters.
+- Spacing must be done with space characters.
+- The following indent style shall be followed (Allman style):
+```
+if(x == y)
+{
+    statement;
+}
+```
+
+### Naming
+
+- Class member method names shall begin with a upper case character (ex.: `int DoSomething();`).
+- Class member variable names shall be prefixed by `m_` (ex.: `int m_member = 0;`).
+
+### Constructors and Destructors
+
+- Empty ctors and dtors definitions are not permitted.
+- Use direct member initialization when possible.
+- If an empty default ctor is needed, it must be declared as `default` in the class declaration.
+- Empty virtual dtors must be marked as `default` in the class declaration.
+
+### Override Keyword
+
+All methods overriding a virtual method from a base class shall be annotated with `override` and must not be marked as `virtual`.
+
+**Exception**: dtors shall be marked as `virtual` and not `override`.
+
+### IOP HLE Modules
+
+- **Module Methods**: All parameters for must be passed as `uint32`. Pointer parameters must also be passed as `uint32` and the name of the parameter must be prepended with `Ptr` (ie. `stringPtr`). When used, return values must be `int32`.
+
+## Objective-C Coding Guidelines
+
+### Naming
+
+- Interface member method names shall begin with a lower case character (ex.: `-(int)doSomething;`).