Fix up pthread_kill header include.
Update .gitignore
some basic numerical representation parsing of un/signed 32/64
More updates for parsing ASN strings.
MemExtent ltrim/rtrim and string find/startswith/endswith tests
Cleanup

  - remove IOVector (prefer MemExtent for now)
  - remove SocketMsg (work on Packet interface to come)
  - remove oldfiledescriptor
Fiber fixes.

The long term usefulness of this particular fiber implementation is
not yet clear to me.

  - Properly include <limits>.
  - -DFORTIFY_SOURCE=2 and -O2 doesn't work with this fiber
    implementation and stack switching tricks.
Some python2 strictnesses...
MemExtent::contentEquals()
Don't segfault on nullptr construction of MemExtent
Tinkering with UPnP things

  - SocketIO::sendTo()
  - SocketIO::recvFrom()
Minor MemExtent fiddling.

  - return buffer sent in SocketIO::sendTo().
UPnP fiddling

- reorg to fibers
- trying IPv6 as well
Continued conversion to StringPiece from std::string
git push/pull ... master
More StringPiece-ification
partial move of InetPrefixes to use StringPiece
More StringPiece-ification of core/net things.
Rework command line parsing and calling.

Also:  "cidr enumerate as" cmdline option.
Some minor zed5util cleanup.