* src/ta/taexplicit.hh (ta_explicit): Take a boolean to tell whether
the tgba is owned.
* src/ta/taexplicit.cc, src/ta/tgtaexplicit.cc,
src/ta/tgtaexplicit.hh: Likewise.
* src/ta/taexplicit.cc (~ta_explicit): Adjust destruction.
* src/tgbatest/ltl2tgba.cc: Adjust usage.
* src/taalgos/minimize.cc: Likewise.