Improve printing of :for expressions
Update profile.c
Add a few items to NEWS.md
isvalidss Nth try
Hopefully fix #7549
Avoid out of bounds access in arpack neupd_wrapper
Initialize the vector of eigenvalues passed to neupd with zeros.
Initialize with NaN values
use isnan, and 0 instead of zero
Correct typo in matrix/factorization.jl

elemenary->elementary
Also trivial "$(m)" -> "$m" change
Add release-candidate-checklist make target

This attempts to document and automate a checklist for producing a
release candidate, to the extent that this is possible.
release-candidate-checklist now depends on release

Also reorder documentation build so that helpdb.jl comes last. Should be
easier to see if the helpdb build was bad and printed a warning.
Add stringent document testing to checklist
Update manual checklist items
Run test suite as part of checklist
Run examples and benchmarks as part of checklist
Make source-dist tarballs