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()
gf store: added C implementation of Store.sum()
store_ext.c: improved error handling
moment_tensor: magnitude and moment args for random_dc()
misfit setups: changed guts-type of domain to StringChoice
seismosizer engine: cache discretized source models
Store.t(): allow source/targets as input arguments
guts: allow for tuple with arbitrary length
seismosizer: added double-DC source model
seismosizer: added clone() and __getitem__ methods to Source
seismosizer: make get_engine() reuse global engine
added guts' preliminary Dict class
seismosizer: improved Range and SourceGrid classes
yaml/guts: use 'pf' namespace everywhere
crust2x2: use new-style classes
gf: fixed vicinity function
guts: fixed a problem with storing bool values as attributes