Recent changes in OpenBSD made my laptops share different (althought
correctly calculated) DPIs. Add an script and rework X resources loading
so:
1. load ~/.Xdefaults into xrdb for baseline
2. run the script to compute a DPI and xterm's faceSize so it respects
some values previously defined in this repo
As an upside, now XTerm.VT100.faceSize can be queried, so use that in
hlwm theme.
