Way to prevent entering interactive mode when run from scripts

[ceresek]

Code can use special instruction to enter interactive mode. When run from script, this usually creates issues (simulation may appear to hang when in fact it is just waiting for input). We should have a way to avoid this:

• an extra command line switch that would make any attempt to enter interactive mode exit the simulator
• checking whether we have interactive input using isatty
• ... ?

[lbulej]

The check using isatty() looks like a good solution...