Add support for W (weak until) and M (strong release) operators.

* src/ltlast/binop.cc, src/ltlast/binop.cc: Add support for
these new operators.
* src/ltlparse/ltlparse.yy, src/ltlparse/ltlscan.ll: Parse them.
* src/ltltest/reduccmp.test: Add new tests for W and M.
* src/ltlvisit/basicreduce.cc, src/ltlvisit/contain.cc,
src/ltlvisit/lunabbrev.cc, src/ltlvisit/nenoform.cc,
src/ltlvisit/randomltl.cc, src/ltlvisit/randomltl.hh,
src/ltlvisit/reduce.cc, src/ltlvisite/simpfg.cc,
src/ltlvisit/simpfg.hh, src/ltlvisit/syntimpl.cc,
src/ltlvisit/tostring.cc, src/tgba/formula2bdd.cc,
src/tgbaalgos/eltl2tgba_lacim.cc, src/tgbaalgos/ltl2taa.cc,
src/tgbaalgos/ltl2tgba_fm.cc, src/tgbaalgos/ltl2tgba_lacim.cc:
Add support for W and M.
* src/tgbatest/ltl2neverclaim.test: Test never claim output
using LBTT, this is more thorough.  Also we cannot use -N
any more in the spotlbtt.test.
* src/tgbatests/ltl2tgba.cc: Define M and W for ELTL.
* src/tgbatest/ltl2neverclaim.test: Test W and M, and use
-DS instead of -N, because lbtt-translate does not want
to translate these operators for tools that masquerade as Spin.

src/tgbatest/spotlbtt.test

@@ -208,9 +208,9 @@ Algorithm
 
 Algorithm
 {
-   Name = "Spot (Couvreur -- FM), degeneralized, via never claim"
+   Name = "Spot (Couvreur -- FM), degeneralized on states"
    Path = "${LBTT_TRANSLATE}"
-   Parameters = "--spin '../ltl2tgba -F -f -N'"
+   Parameters = "--spot '../ltl2tgba -F -f -t -DS'"
    Enabled = yes
 }
 
@@ -272,9 +272,9 @@ Algorithm
 
 Algorithm
 {
-   Name = "Spot (Couvreur -- FM), pre + post reduction, via never claim"
+   Name = "Spot (Couvreur -- FM), pre + post reduction, degeneralized on states"
    Path = "${LBTT_TRANSLATE}"
-   Parameters = "--spin '../ltl2tgba -F -f -N -R3 -r7'"
+   Parameters = "--spot '../ltl2tgba -F -f -DS -R3 -r7 -t'"
    Enabled = yes
 }
 
@@ -339,8 +339,6 @@ FormulaOptions
   # EquivalencePriority = 0
 
   BeforePriority = 0
-  StrongReleasePriority = 0
-  WeakUntilPriority = 0
 
   DefaultOperatorPriority = 5
 }