* UC0 should restore values pushed by US/TPx
* UC1 should stop when the stack top is a page call
* UC1/2 should restore status pushes by TPx
* UC1/2 should not consume the count for non-call stack frames
* Add support for UC3 command
- nact.h and xsystem35.h no longer include scenario.h
- Removed `sys_*` aliases in nact.h
- sys_getString() and sys_getConstString() are moved to
scenario.c as sl_getString() and sl_getConstString()
- DEBUG_COMMAND macros are now defined in scenario.h