fix error message format for d-to-c translator
fix operator '?' so values returned are checked for correctness

If a user defines a new class X and defines a new comparison
operation method function for X?X, it should return one of the
following symbols: <, >, ==, incomparable.  This is now enforced,
to prevent confusion, in that an error message signals an incorrect
return value.
fix the documentation of the comparison operator x?y
adjust .gitignore files
amend the INSTALL file
add a helpful error message
update INSTALL
change to integral closure of ideal (code by Doug Leonard), part I.

This code will replace the original integralClosure of Ideal code.
Merge branch 'master' of https://github.com/Macaulay2/M2
update INSTALL
Merge branch 'master' of github.com:Macaulay2/M2
update INSTALL
update INSTALL
integral closure of ideals, part II (with Doug Leonard)
Merge branch 'master' of https://github.com/Macaulay2/M2
update README file
Merge branch 'master' of github.com:Macaulay2/M2
add appropriate .gitignore files

in the appropriate directories, making up for
commit f0c85c3311f4254b21de5b5dca38208ae884f689
Merge branch 'master' of github.com:Macaulay2/M2