Add per-named-item overlay ability in res xml.

Fixes 1899451.
Also errors out if you add a bag via an overlay (which would renumber
resources).  Note that you can still add elements within the bag as they are
not issued resource IDs.  So for example you can now modify the framework
themes.xml file without copying the entire file.

All bag types are now modifable except non-named bag types (how would you
address which element to replace?):
    array
    string_array
    integer_array
diff --git a/tools/aapt/ResourceTable.cpp b/tools/aapt/ResourceTable.cpp
index 66607a3..770c7d8 100644
--- a/tools/aapt/ResourceTable.cpp
+++ b/tools/aapt/ResourceTable.cpp
@@ -729,6 +729,7 @@
             String16 curType;
             int32_t curFormat = ResTable_map::TYPE_ANY;
             bool curIsBag = false;
+            bool curIsBagReplaceOnOverwrite = false;
             bool curIsStyled = false;
             bool curIsPseudolocalizable = false;
             bool localHasErrors = false;
@@ -1171,6 +1172,7 @@
                 curTag = &array16;
                 curType = array16;
                 curIsBag = true;
+                curIsBagReplaceOnOverwrite = true;
                 ssize_t formatIdx = block.indexOfAttribute(NULL, "format");
                 if (formatIdx >= 0) {
                     String16 formatStr = String16(block.getAttributeStringValue(
@@ -1189,12 +1191,14 @@
                 curType = array16;
                 curFormat = ResTable_map::TYPE_REFERENCE|ResTable_map::TYPE_STRING;
                 curIsBag = true;
+                curIsBagReplaceOnOverwrite = true;
                 curIsPseudolocalizable = true;
             } else if (strcmp16(block.getElementName(&len), integer_array16.string()) == 0) {
                 curTag = &integer_array16;
                 curType = array16;
                 curFormat = ResTable_map::TYPE_REFERENCE|ResTable_map::TYPE_INTEGER;
                 curIsBag = true;
+                curIsBagReplaceOnOverwrite = true;
             } else {
                 SourcePos(in->getPrintableSource(), block.getLineNumber()).error(
                         "Found tag %s where item is expected\n",
@@ -1229,9 +1233,10 @@
                 }
 
                 if (!localHasErrors) {
-                    err = outTable->startBag(SourcePos(in->getPrintableSource(), block.getLineNumber()),
-                                             myPackage, curType, ident, parentIdent, &curParams, 
-                                             overwrite);
+                    err = outTable->startBag(SourcePos(in->getPrintableSource(),
+                            block.getLineNumber()), myPackage, curType, ident,
+                            parentIdent, &curParams,
+                            overwrite, curIsBagReplaceOnOverwrite);
                     if (err != NO_ERROR) {
                         hasErrors = localHasErrors = true;
                     }
@@ -1529,6 +1534,7 @@
                                  const String16& name,
                                  const String16& bagParent,
                                  const ResTable_config* params,
+                                 bool overlay,
                                  bool replace, bool isId)
 {
     status_t result = NO_ERROR;
@@ -1549,7 +1555,12 @@
                sourcePos.file.striing(), sourcePos.line, String8(type).string());
     }
 #endif
-    
+    if (overlay && !hasBagOrEntry(package, type, name)) {
+        sourcePos.error("Can't add new bags in an overlay.  See '%s'\n",
+                        String8(name).string());
+        return UNKNOWN_ERROR;
+    }
+
     sp<Entry> e = getEntry(package, type, name, sourcePos, params);
     if (e == NULL) {
         return UNKNOWN_ERROR;
@@ -1571,7 +1582,7 @@
         return result;
     }
 
-    if (replace) { 
+    if (overlay && replace) { 
         return e->emptyBag(sourcePos);
     }
     return result;