Automatically initialize all variables with fixed values

[alastairreid]

A recent spec bug turned out to be due to an uninitialized ASL variable. Or, more accurately, an uninitialized field of a local variable.

This was hard to reproduce because it changed if you piped output to a file or if you compiled on a different machine.

To make things more consistent, it would be nice if ASLi initialized all variables when it creates them.
And to avoid the risk that the initial value that ASLi chooses happens to make the code work, we could have an option to change the initializer: if it works with initial value of 0 and with initial value of deadbeef or ffffffff, then it is probably ok.

A