Allow negative rationals for test mode RESULT specifications.

Was previously being parsed as a PRISM expression as a fallback,
but the parser currently does not handle big integers.

Test case added. And these tests moved to a new "testing" directory.

prism-tests/bugfixes/normaltestwithrationalresult.prism.props

@@ -1,2 +0,0 @@
-// RESULT: 1503982516387544510687823213516750681753609533738014093985492327446021823341670745201522478360759626261166470522913554557570937367804047825330483938531949304640395637223627199/3552713678800500929355621337890625000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-"p1": P=? [ F s=5 ];

prism-tests/functionality/testing/normaltestwithrationalresult.prism.props

@@ -0,0 +1,5 @@
+// RESULT: 1503982516387544510687823213516750681753609533738014093985492327446021823341670745201522478360759626261166470522913554557570937367804047825330483938531949304640395637223627199/3552713678800500929355621337890625000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+"p1": P=? [ F s=5 ];
+
+// RESULT: -1503982516387544510687823213516750681753609533738014093985492327446021823341670745201522478360759626261166470522913554557570937367804047825330483938531949304640395637223627199/3552713678800500929355621337890625000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+"neg_p1": -P=? [ F s=5 ];

prism/src/parser/ast/Property.java

@@ -397,7 +397,7 @@ public class Property extends ASTElement
 					doubleExp = Double.NaN;
 				}
 				// See if it's a fraction
-				else if (strExpectedValue.matches("[0-9]+/[0-9]+")) {
+				else if (strExpectedValue.matches("-?[0-9]+/[0-9]+")) {
 					doubleExp = new BigRational(strExpectedValue).doubleValue();
 					simple = false;  // complex expression
 				}