fallback stdin input when parameter not set

aconversions2/src/aconversion.cpp

aderivation2/src/aderivation.cpp

adeterminize2/src/adeterminize.cpp

adiff2/src/adiff.cpp

aintegral2/src/aintegral.cpp

arun2/src/arun.cpp

astat2/src/astat.cpp

astringology2/src/astringology.cpp

makefile