Fix Pod coverage warnings about constants and new internal methods
Skip unit tests involving closures in RserveClient macro tests

Closure REXPs don't have a Perl value representation and die on
`to_pl`, so it's better to not even run them.
Release version 0.10

Changes since v0.092:

- Implement complex vector SEXPs (#30)
- Implement closure SEXPs (#29, #32, #34, #35, #36, #38)
- Implement expression SEXPs (#26)
- Implement special environments global, base, and empty (#31, #33)
- Allow configuring Rserve host from WebWork settings
- Add graceful failure in WWk macros if Rserve host is not configured
- Fix parsing of special row names (#39)