SMCRoute v2.5.6

Despite the new smcroutectl batch mode feature, this is primarily a
bug fix release. Most notably #183 and #187.

Changes

• Add smcroutectl batch support, issue #189. Based on the IPC support
  added in issue #185, by Alexey Smirnov:

    ~$ sudo smcroutectl -b <<-EOF
           join eth0 225.1.2.3
           add eth0 192.168.1.42 225.1.2.3 eth1 eth2
           rem eth1 225.3.4.5 eth3
           leave eth1 225.3.4.5
           EOF
    ~$
  

Fixes

• Fix #178: invalid systemd daemon type Simple/Notify vs simple/notify
• Fix #179: typo in wildcard routes section of README
• Fix #180: minor typo in file and directory names in documentation
• Fix #183: casting in IPC code hides error handling of recv()
• Fix #186: NULL pointer dereference in utimensat() replacement
  function. Found accidentally by Alexey Smirnov. Only triggered on
  systems that don't have a native utimensat() in their C-library, or
  if you try to build SMCRoute without using its own build system ...
• Fix #187: strange behavior joining/leaving the same group
• Fix #192: typo in README