wmaker: Reduce wakeups to zero

wmaker: Reduce wakeups to zero

This patch removes wmaker from PowerTop's shame list, where
it appeared with ~3-4 wakeups/second.

It adds the linux kernel's dnotify mechanism (adapted from
the example in Documentation/dnotify.txt in the kernel source),
to detect when a configuration file in ~/GNUStep/Defaults has
changed to load it again on-the-fly. For me it usually means that
modifications to ~/GNUStep/Defaults/WMRootMenu via the 'genmenu'
script are automatically detected and loaded.

The use of dnotify makes the ancient behaviour of polling unecessary
and cuts down the wakeups count.

Other 'apparently' useless timers are also deleted and it's been almost
one year now that I use this patched exclusively without problems, so
I am pretty sure that it doesn't hurt to remove them.

The end result of all this is that wmaker generates 0 (zero) wakeups
when idle in a Linux system.

Signed-off-by: Carlos R. Mafra <crmafra@ift.unesp.br>