Update Memory.jack

[schn2017]

The web IDE will throw the following error "OS subroutine Memory.alloc must follow the interface Array alloc(int)" when the return type is an int instead of an Array.

The web-ide expects the return type to be of type "Array" as defined in web-ide/simulator/src/vm/builtins.ts. See lines 205 to 213 of that file. The snippet is also attached below.

"Memory.alloc": {
   func: (memory, os) => {
      const [size] = getArgs(memory, 1);
      return os.memory.alloc(size);
   },
    args: ["int"],
    returnType: "Array",
    type: "function",
},

[schn2017]

The zip folder that is downloaded through google projects should probably be updated too.