fomosto export: use a better default name when user specifies directory
cake: use potential interpolation selectively for P and S

fixes a problem when there is a gradient in either P or S
trace.correlate: fixed a problem with newer scipy versions
parimap: prevent a hang in Process.join()
snuffler: can now specify stream selectors in raw slinktool format

If there is an underscore in the selector part of the seedlink url,
all stream selectors are passed to slinktool's -S option as they are.
No info query is done in this case.
sac: fixed incorrect handling of null-terminated header values
Merge branch 'master' of git://github.com/emolch/pyrocko
fomosto view --show-phases adds phase markers