Improved the Lua documentation

- Lua documentation now needs a string giving the arguments list.
- When generating documentation first prints the command list and then prints
  the documentation for each command.
- Supports fixed max line length (set to 80)
- Uses four blank spaces as padding (easily replacable)

include/openspace/scripting/scriptengine.h

@@ -42,6 +42,7 @@ public:
 		struct Function {
 			std::string name;
 			lua_CFunction function;
+			std::string argumentText;
 			std::string helpText;
 		};
         std::string name;