Update to 0.4.0:

Arnaud Fontaine (3):
      Pick-up changes in m4 submodule as it's better to have all util repos at same m4 level.
      Remove old/outdated documentation crufts.
      Release 0.4.0

Bastien Dejean (1):
      Duplicate keycodes are unnecessary

Michael Stapelberg (1):
      autogen.sh: verify that git submodules are initialized

Uli Schlachter (1):
      Fix handling of error connections

(wiz)