If -debug option is specified, xsystem35 enables built-in debugger. It
optionally loads debug information from *SA.ALD.symbols file (generated
by xsys35c), and drops into a debugger REPL.
Currently the debugger supports:
- Simple breakpoints
- Backtrace
- Single-step execution (step into / step over)
- Printing variables
Also, when the debugger is enabled SIGINT breaks execution and enters a
REPL.