WASM: add support of Character.toLowerCase/toUpperCase. Add _ prefix to names in c output

classlib/src/main/java/org/teavm/classlib/java/lang/TCharacter.java

@@ -16,6 +16,8 @@
 package org.teavm.classlib.java.lang;
 
 import org.teavm.classlib.impl.unicode.UnicodeHelper;
+import org.teavm.interop.DelegateTo;
+import org.teavm.interop.Import;
 import org.teavm.platform.Platform;
 import org.teavm.platform.metadata.MetadataProvider;
 import org.teavm.platform.metadata.StringResource;
@@ -231,18 +233,34 @@ public class TCharacter extends TObject implements TComparable<TCharacter> {
         return (char) toLowerCase((int) ch);
     }
 
+    @DelegateTo("toLowerCaseLowLevel")
     public static int toLowerCase(int ch) {
         return Platform.stringFromCharCode(ch).toLowerCase().charCodeAt(0);
     }
 
+    private static int toLowerCaseLowLevel(int codePoint) {
+        return toLowerCaseSystem(codePoint);
+    }
+
+    @Import(module = "runtime", name = "towlower")
+    private static native int toLowerCaseSystem(int codePoint);
+
     public static char toUpperCase(char ch) {
         return (char) toUpperCase((int) ch);
     }
 
+    @DelegateTo("toUpperCaseLowLevel")
     public static int toUpperCase(int codePoint) {
         return Platform.stringFromCharCode(codePoint).toUpperCase().charCodeAt(0);
     }
 
+    private static int toUpperCaseLowLevel(int codePoint) {
+        return toUpperCaseSystem(codePoint);
+    }
+
+    @Import(module = "runtime", name = "towupper")
+    private static native int toUpperCaseSystem(int codePoint);
+
     public static int digit(char ch, int radix) {
         return digit((int) ch, radix);
     }

core/src/main/java/org/teavm/backend/wasm/render/WasmCRenderer.java

@@ -83,7 +83,7 @@ public class WasmCRenderer {
 
         for (WasmFunction function : module.getFunctions().values()) {
             if (function.getExportName() != null && function.getExportName().equals("main")) {
-                line(function.getName() + "(0);");
+                line(function.getName() + "(1);");
             }
         }
 

core/src/main/java/org/teavm/backend/wasm/render/WasmCRenderingVisitor.java

@@ -1049,7 +1049,7 @@ class WasmCRenderingVisitor implements WasmExpressionVisitor {
         String result = localVariableNames[local.getIndex()];
         if (result == null) {
             if (local.getName() != null) {
-                result = local.getName();
+                result = "_" + local.getName();
             } else {
                 result = "localVar" + local.getIndex();
             }