'Switch' statements with single case converted to 'if', other warnings fixed

src/org/jetbrains/java/decompiler/modules/decompiler/ExitHelper.java

@@ -80,8 +80,7 @@ public class ExitHelper {
         }
       }
 
-      switch (stat.type) {
-        case Statement.TYPE_IF:
+      if (stat.type == Statement.TYPE_IF) {
         IfStatement ifst = (IfStatement)stat;
         if (ifst.getIfstat() == null) {
           StatEdge ifedge = ifst.getIfEdge();

src/org/jetbrains/java/decompiler/modules/decompiler/MergeHelper.java

@@ -376,8 +376,7 @@ public class MergeHelper {
       return stat;
     }
 
-    switch (stat.type) {
-      case Statement.TYPE_SEQUENCE:
+    if (stat.type == Statement.TYPE_SEQUENCE) {
       for (int i = stat.getStats().size() - 1; i >= 0; i--) {
         Statement tmp = getLastDirectData(stat.getStats().get(i));
         if (tmp == null || !tmp.getExprents().isEmpty()) {