Convert last "prog" exercises as functions exercises (intermediate commit)

subjects/doppelgangerprog.en.md

@@ -18,9 +18,9 @@ func DoppelGanger(s, substr string) int {
 package main
 
 import (
-	piscine ".."
-
 	"fmt"
+
+	piscine ".."
 )
 
 func main() {

subjects/findprevprimeprog.en.md

@@ -22,9 +22,9 @@ Here is a possible [program](TODO-LINK) to test your function :
 package main
 
 import (
-	piscine ".."
-
 	"fmt"
+
+	piscine ".."
 )
 
 func main() {

subjects/halfcontest.en.md

@@ -13,7 +13,7 @@ Contest cannot finish before it was started.
 ### Expected function
 
 ```go
-func Halfcontest(h1, m1, h2, m2 int) int {
+func HalfContest(h1, m1, h2, m2 int) int {
 
 }
 ```
@@ -25,12 +25,16 @@ Here is a possible program to test your function :
 ```go
 package main
 
-import "fmt"
+import (
+	"fmt"
+
+	piscine ".."
+)
 
 func main() {
-	fmt.Println(Halfcontest(1, 15, 3, 33))
+	fmt.Println(piscine.HalfContest(1, 15, 3, 33))
-	fmt.Println(Halfcontest(10, 3, 11, 55))
+	fmt.Println(piscine.HalfContest(10, 3, 11, 55))
-	fmt.Println(Halfcontest(9, 2, 11, 3))
+	fmt.Println(piscine.HalfContest(9, 2, 11, 3))
 }
 ```
 

tests/go/solutions/halfcontest.go

@@ -1,6 +1,6 @@
 package correct
 
-func Halfcontest(h1, m1, h2, m2 int) int {
+func HalfContest(h1, m1, h2, m2 int) int {
 	t1 := h1*60 + m1
 	t2 := h2*60 + m2
 	t2 = (t2 + t1) / 2

tests/go/test_findprevprime.go

@@ -10,6 +10,6 @@ import (
 func main() {
 	a := append(z01.MultRandIntBetween(0, 99999), 5, 4, 1)
 	for _, elem := range a {
-		z01.Challenge("FindPrevPrimeProg", student.FindPrevPrime, correct.FindPrevPrime, elem)
+		z01.Challenge("FindPrevPrime", student.FindPrevPrime, correct.FindPrevPrime, elem)
 	}
 }

tests/go/test_halfcontest.go

@@ -29,6 +29,6 @@ func main() {
 	}
 
 	for _, arg := range table {
-		z01.Challenge("HalfContestProg", student.Halfcontest, correct.Halfcontest, arg.h1, arg.m1, arg.h2, arg.m2)
+		z01.Challenge("HalfContest", student.HalfContest, correct.HalfContest, arg.h1, arg.m1, arg.h2, arg.m2)
 	}
 }