Fix get_datatype_info_c::is_subrange(), which did not work when using base type! (we now use get_equivtype() instead of get_base_type() )

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