* Object layout and parsing are done in the vm::obj module
* Add MemCursor, a wrapper around the std::io::Cursor type for walking
through VM memory
* Add vm::tick module for containing the Vm::tick() method
implementation, since it's pretty big
* Instructions are now variable-sized, and are read lazily,
one-at-a-time directly from memory.
* Add VM runtime error structure
* Probably some other stuff I forgot
Signed-off-by: Alek Ratzloff <alekratz@gmail.com>
