Support long jumps inside an expression

[danysirota]

We are generating really long expressions (>1MB) and using conditionals there that can cause more than 64KB jumps. Today, the args of the opcodes are 2 bytes and long jumps are truncated to this size. When running the expression, the VM jumps (actual_offset % 64Kb) and runs invalid opcodes.

[antonmedv]

Wow! Such a big expression. Amazing) So, yes. this is a limitation of the current VM.

I see to possible solutions:

1. Use bigger opcodes (this will require proper benchmarking to make sure be op size performance as the same level).
2. Or panic on trying to generate too big jump.

[antonmedv]

Fixed! I refactored vm. Now it uses int for args. So, jumps can be really long. Also it got 50% faster).