Support valued assignment and modifying assignment in java

[MichaelRFairhurst]

Supporting java's native arrays will be difficult, so at least for now it all compiles to List

this means when I write in wake

 arr[5] += 1;

it needs to compile to

arr.set(5, arr.get(5) + 1);

This needs to be supported for +=, -=, /=, etc, as well as := which should look like

int temp = 6;
arr.set(5, 6); return 6;

Have to be careful of sideeffects on the left side and moments when we don't have the luxury of doing multilpe statements.