update autoconf version in our makefile
my makefile
insist on autoconf >= 2.68 now, for the sake of mpir
update .gitgnore
remove obsolete shell script for use with svn
add an option EXECSTACK=no, part 4

improved instructions for user
newer linux makefile target
Merge branch 'master' of https://github.com/Macaulay2/M2
Merged Macaulay2/M2 master into linalg branch, fixed conflicts

Conflicts:
	.gitignore
	M2/BUILD/mike/Makefile
	M2/Macaulay2/m2/exports.m2
	M2/libraries/gtest/Makefile.in
Merge remote-tracking branch 'm2/master' into linalg

Conflicts:
	M2/Macaulay2/bin/Makefile.in
Fixed.  I’m not sure why I get this conflict…
add linker option for non-executable stack

as well as tests in the configure script for whether the option (and some
others) are accepted by the compiler.

The makefile bin/Makefile.in applies several other compiler flags
that ought to be tested similarly.
Merge branch 'master' of github.com:Macaulay2/M2
add linker option for non-executable stack

as well as tests in the configure script for whether the option (and some
others) are accepted by the compiler.

The makefile bin/Makefile.in applies several other compiler flags
that ought to be tested similarly.
add text to INSTALL instructions
stop using the execstack program

since it fails on NFS-mounted file systems, and we now
have a better way to do it with an linker option
update INSTALL instructions
update INSTALL instructions
inicial test.structure.single-package.variant with base branch Mike/linalg
bugfix
export functions missed