#110 p4eclipse occasionally forgets preference setting

[Per Velschow]

I am reporting this against p4eclipse 0.6.24 and Eclipse
3.0 M8.

It seems that p4eclipse occasionally forgets preference
setting 'Show added markers'. I always want this setting
unchecked. Since it is the only non-default setting I use
for p4eclipse, I don't know if the problem simply is that
p4eclipse occasionally get its settings reverted to the
default.