Log Message:
wm/emwm: few enhancements

* Switch to a unified makefile, replacing per-platform makefiles.
* Standardise build environment.
* Add emwmrc(4) man page.
* Include sample gtk 2/3 configuration and Xresources files.
* Include project's additional pixmaps.
* Remove MESSAGE and install system-wide configuration at the
  right location.

Revision bumped.