stdlib: sync with upstream.

* lib/specl/std.lua: Improved Object implementation.
Adjust all clients.
* lib/specl/matchers.lua (Matcher::_type): Capitalize typename to
match stdlib pattern.
Adjust all clients.
* lib/specl/shell.lua (Command::_type): Likewise.
(Process::_type): Likewise.
* lib/specl/util.lua (type_check): Detect an Object based type
with `type (x) == "table" and Object.type (x) ~= "table"` rather
than encoding knowledge about the object layout (which just
changed with this update, and broke here in a hard to find way!).
* specs/shell_spec.yaml: Adjust for capitalized type names.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
specs: correct output from instantiate_a matcher.

Without this changeset, output from failed instantiate_a matches
aresmooshedtogetherlikethis.
* specs/spec_helper.lua (matchers.instantiate_a::format_actual):
Add missing leading space.
(matchers.instantiate_a::format_expect): Add missing leading space,
and trailing comma.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>