message: update version and year info
diff: dnl require autoconf 2.60 (AS_ECHO/AS_ECHO_N)
  AC_PREREQ([2.60])
  define(_CLIENT_VERSION_MAJOR, 0)
  -define(_CLIENT_VERSION_MINOR, 8)
  -define(_CLIENT_VERSION_REVISION, 99)
  +define(_CLIENT_VERSION_MINOR, 6)
  +define(_CLIENT_VERSION_REVISION, 0)
  define(_CLIENT_VERSION_BUILD, 0)
  define(_CLIENT_VERSION_IS_RELEASE, false)
  -define(_COPYRIGHT_YEAR, 2013)
  +define(_COPYRIGHT_YEAR, 2017)
  AC_INIT([Peercoin],[_CLIENT_VERSION_MAJOR._CLIENT_VERSION_MINOR._CLIENT_VERSION_REVISION],[info@peercoin.net],[peercoin])
  AC_CONFIG_AUX_DIR([build-aux])
  AC_CONFIG_MACRO_DIR([build-aux/m4])
  