This brings in the new HCL extension functions "try", "can", and
"convert", along with the underlying HCL and cty infrastructure that allow
them to work.
This contains a fix for a panic in Value.HasElement when used on a set
value whose element type is an object or tuple.
A few other minor dependency upgrades came long for the ride.
This brings in a bugfix for analyzing variables inside relative traversal
expressions in HCL, and a cosmetic bugfix in cty for GoString of
cty.NullVal(cty.DynamicPseudoType).
This also updates some other packages, as a result of running "go get -u".
This is largely minor bugfixes for issues found since we last updated the
vendoring. There are some new features here that Terraform is not yet
using and thus present little risk.
In particular this includes the HCL-JSON spec change where arrays can now
be used at any level in a block label structure, to allow for preserving
the relative order of blocks.