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.
This new version supports a conversion from object types to map types,
which is important for Terraform because HCL2 { ... } syntax produces
objects but lots of Terraform attributes require maps.
Martin Atkins