Add support for FB call semantics of 'S' and 'R' IL operators!
Remove segfaults when analysing buggy IL code (IL operators with no operands).

STD_TEST.st
STD_RESSOURCE.c
LOCATED_VARIABLES.h
POUS.c
test
STD_CONF.c
SFC_TEST.st
test.exe
plc.st
POUS.h
VARIABLES.csv