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.
