Fix PCSG handling

src/grammar_base.jl

@@ -140,6 +140,20 @@
     return grammar.log_probabilities[index]
 end
 
+
+"""
+    make_probabilistic!(grammar::AbstractGrammar)
+
+If the grammar is not probabilistic yet, initializes the grammar with uniform probabilities per type. If the grammar is alread probabilistic, no changed are made.
+"""
+function make_probabilistic!(grammar::AbstractGrammar)
+    if isprobabilistic(grammar)
+        @warn "Grammar is already probabilistic. The grammar will not be changed."
+    else
+        grammar.log_probabilities = [log(1 / length(grammar.bytype[grammar.types[index]])) for index in 1:length(grammar.rules)]
+    end
+end
+
 """
     probability(grammar::AbstractGrammar, index::Int)::Real