Update tealdbg for TEAL 4

[jasonpaulos]

Summary

TEAL v4 now allows looping, function calls, and has some additional opcodes. We need to make sure the debugger is able to understand these new changes.

Scope/Requirements

Test that the debugger can handle the new feature from TEAL 4. I suspect the following may require debugger changes:

• Changes to foreign app/asset/account indexing
• Function calls & backward branches

If any changes are required, make them.

Urgency/Relative Priority

Required to ensure TEAL 4 programs can be debugged properly.

[onetechnical]

As you're stepping it should tell how much cost you've used.

[jannotti]

The debugger could be extended to show the "hidden" call stack that callsub/retsub uses.