Add Rosetta Code Generator/Exponential test

Also ensure all RC tests are described consistently, with a forward
slash (the way they are named on the site) rather than a hyphen (the
way they have to be named as files).

rosettacode/Generator-Exponential.result.json

@@ -0,0 +1 @@
+null

rosettacode/Generator-Exponential.ursa

@@ -0,0 +1,37 @@
+let count = gen() {
+    let n = 0
+    loop {
+        yield n
+        n := n + 1
+    }
+}
+
+let powers = gen(m) {
+    for n of count() {
+        yield n ** m
+    }
+}
+
+let filtered = gen(s1, s2) {
+    let v = s1()
+    let f = s2()
+    loop {
+        if v > f {
+            f := s2()
+            continue
+        } else if v < f {
+            yield v
+        }
+        v := s1()
+    }
+}
+
+
+let squares = powers(2)
+let cubes = powers(3)
+let f = filtered(squares, cubes)
+
+// Drop first 20 items.
+for i of range(20) {f()}
+// Print next 10 items.
+for i of range(10) {print(f())}

src/ursa/examples.test.ts

@@ -282,10 +282,21 @@ Fizz
 98
 Fizz
 Buzz`)
-ursaTest('Hello world-Text', 'rosettacode/Hello world-Text', [], 'hello woods!')
+ursaTest('Generator/Exponential', 'rosettacode/Generator-Exponential', [], `\
+529
+576
+625
+676
+784
+841
+900
+961
+1024
+1089`)
+ursaTest('Hello world/Text', 'rosettacode/Hello world-Text', [], 'hello woods!')
 // Not run, as this program does not terminate
 // ursaTest('Integer sequence', 'rosettacode/Integer sequence')
-ursaTest('Loops-Continue', 'rosettacode/Loops-Continue', [], `\
+ursaTest('Loops/Continue', 'rosettacode/Loops-Continue', [], `\
 1, 2, 3, 4, 5
 6, 7, 8, 9, 10`)