added test cases for computation with abstract syntax terms

testsuite/runtime/eval/eval.gfs.gold

@@ -0,0 +1,50 @@
+\v0 -> v0 1
+
+
+
+? 1
+
+
+
+? 1
+
+
+
+unknown variable unknown_var
+
+unknown variable unknown_var
+
+literal of function type
+
+f 1 2
+
+
+
+\v0 -> v0
+
+
+
+?666
+
+
+
+f
+
+
+
+f 1 2
+
+
+
+literal of function type
+
+2
+
+
+
+g 0
+
+
+
+\v0 -> g v0
+