Adds a "Debug" rendering opcode which prints out a debug string.

Set a breakpoint in vsRenderDebug to stop at a breakpoint when that
particular rendering command is executed;

Can be useful for debugging rendering troubles in complicated scenes.
Adds "Find()" function to vsArray and vsArrayStore.

Also adds 'npos' to indicate failure to find an item.

RemoveItem() now returns a boolean value to indicate whether an item was
removed on vsArray, vsArrayStore, vsLinkedList, and vsLinkedListStore.