Feature/embed hiredis

[eddelbuettel]

@armstrtw If you have a moment at work on Monday, look this over -- should be fine

I finally gave up on CRAN's ability to eventually procure a libhiredis where it hadn't yet -- ie macOS -- so I stuck in here as a fallback. On normal systems we still use an external hiredis.

Also made RcppMsgPack unconditional at the C++ side as the package already pulled it in.

[armstrtw]

I'll check it out. Also if you feel like waiting another day or so, I plan to add a few more of the commands for hashes. Sometimes cran seems a bit finicky about accepting multiple releases in a short period.

[eddelbuettel]

Sure, just give me a heads-up as you just did, and as we (ahem, ahem, ...) suggest in some Contributing.md (different repo, same idea): issue ticket first is always a good plan so that everybody is on the same page.

Also, if I may, before you branch next let me merge this so that we have clean history graphs.

[eddelbuettel]

@armstrtw Did you get a chance to look at it yet?

[armstrtw]

Sorry for the delay. This compiles/installs and produces expected results for my local scripts. Was there anything in particular that you wanted me to test?