class gspn_environment, and move it to ...
* src/ltlenv/declenv.cc, src/ltlenv/declenv.hh: .. this new file
as class declarative_environment.
* src/ltlenv/Makefile.am (ltlenv_HEADERS): Add declenv.hh.
(libltlenv_la_SOURCES): Add declenv.cc.
* iface/gspn/dottygspn.cc, iface/gspn/dottyssp.cc,
iface/gspn/gspn.cc, iface/gspn/gspn.hh, iface/gspn/ltlgspn.cc,
iface/gspn/ssp.cc, iface/gspn/ssp.hh: Adjust references
to declarative_environment.
* iface/gspn/eesrg.cc, iface/gspn/eesrg.hh,
iface/gspn/dottyeesrg.cc: Rename as ...
* iface/gspn/ssp.cc, iface/gspn/ssp.hh, iface/gspn/dottyssp.cc:
... these. Adjust all classes and function names.
* iface/gspn/ltlgspn.cc, iface/gspn/Makefile.am: Adjust all classes
filenames and function names.
* m4/gspnlib.m4: Define WITH_GSPN_SSP and LIBGSPNSSP_LDFLAGS.
