file open/close functions can process any stream *filename*
run.single() to run a propka calculation without script

- can pass a single pdffile (or stream(!))
- added options lib.loadOptions() to pass opt string
new version.MDAnalysis: enable eps_surface = 80

For testing: use a surface dielectric of 80 for frames that
come from MD simulations (instead of 160 as in PROPKA 3.1).
Olsson et al JCTC 7 (2011) suggest that this might be a sensible
option if the input structures come from MD/NMR and not crystallography.