drop unnecessary Makefiles

Today examples/Makefile.am suffices for building all programs in examples/.
build examples always
malloc.h is deprecated
-Wformat-security
Neither examples nor tutorial are assumed to be installed
build tutorial always
bug fix for indefinitely; reported by geraldine celliere
replaed outdated AC_PROG_LIBTOOL with LT_INIT
updated INSTALL
updated INSTALL
Merge branch 'master' into sundials-2.4.0

in order to catch up with last two months.