resolve some very subtle memory problems under non-ARC

@@ -67,7 +67,7 @@
 {
     if ( ! _imageURLString)
     {
-        NSString *imagerySetString;
+        NSString *imagerySetString = nil;
 
         if (_imagerySet == RMBingImagerySetAerial)
             imagerySetString = @"Aerial";

@@ -103,7 +103,7 @@
         [[NSNotificationCenter defaultCenter] postNotificationName:RMTileRequested object:[NSNumber numberWithUnsignedLongLong:RMTileKey(tile)]];
     });
     
-    __block UIImage *image;
+    __block UIImage *image = nil;
 
     [queue inDatabase:^(FMDatabase *db)
     {
@@ -250,7 +250,7 @@
 
 - (NSString *)legend
 {
-    __block NSString *legend;
+    __block NSString *legend  = nil;
 
     [queue inDatabase:^(FMDatabase *db)
     {
@@ -332,7 +332,7 @@
 
 - (NSString *)shortName
 {
-    __block NSString *shortName;
+    __block NSString *shortName = nil;
 
     [queue inDatabase:^(FMDatabase *db)
     {
@@ -353,7 +353,7 @@
 
 - (NSString *)longDescription
 {
-    __block NSString *description;
+    __block NSString *description = nil;
 
     [queue inDatabase:^(FMDatabase *db)
     {
@@ -374,7 +374,7 @@
 
 - (NSString *)shortAttribution
 {
-    __block NSString *attribution;
+    __block NSString *attribution = nil;
 
     [queue inDatabase:^(FMDatabase *db)
     {

@@ -70,7 +70,7 @@
                                                                            options:0
                                                                              error:nil] retain];
 
-        id dataObject;
+        id dataObject = nil;
         
         if (mapView && (dataObject = [_infoDictionary objectForKey:@"data"]) && dataObject)
         {
@@ -80,7 +80,7 @@
                 {
                     NSURL *dataURL = [NSURL URLWithString:[dataObject objectAtIndex:0]];
                     
-                    NSMutableString *jsonString;
+                    NSMutableString *jsonString = nil;
                     
                     if (dataURL && (jsonString = [NSMutableString stringWithContentsOfURL:dataURL encoding:NSUTF8StringEncoding error:nil]) && jsonString)
                     {
@@ -90,7 +90,7 @@
                             [jsonString replaceCharactersInRange:NSMakeRange([jsonString length] - 2, 2) withString:@""];
                         }
                         
-                        id jsonObject;
+                        id jsonObject = nil;
                         
                         if ((jsonObject = [NSJSONSerialization JSONObjectWithData:[jsonString dataUsingEncoding:NSUTF8StringEncoding] options:0 error:nil]) && [jsonObject isKindOfClass:[NSDictionary class]])
                         {
@@ -146,7 +146,7 @@
 
 - (id)initWithReferenceURL:(NSURL *)referenceURL enablingDataOnMapView:(RMMapView *)mapView
 {
-    id dataObject;
+    id dataObject = nil;
     
     if ([[referenceURL pathExtension] isEqualToString:@"jsonp"])
         referenceURL = [NSURL URLWithString:[[referenceURL absoluteString] stringByReplacingOccurrencesOfString:@".jsonp" 
@@ -198,7 +198,7 @@
     if ([self.infoDictionary objectForKey:@"scheme"] && [[self.infoDictionary objectForKey:@"scheme"] isEqual:@"tms"])
         y = pow(2, zoom) - tile.y - 1;
 
-    NSString *tileURLString;
+    NSString *tileURLString = nil;
 
     if ([self.infoDictionary objectForKey:@"tiles"])
         tileURLString = [[self.infoDictionary objectForKey:@"tiles"] objectAtIndex:0];
@@ -212,7 +212,7 @@
 
     if (_imageQuality != RMMapBoxSourceQualityFull)
     {
-        NSString *qualityExtension;
+        NSString *qualityExtension = nil;
 
         switch (_imageQuality)
         {
@@ -282,7 +282,7 @@
 {
     id bounds = [self.infoDictionary objectForKey:@"bounds"];
 
-    NSArray *parts;
+    NSArray *parts = nil;
 
     if ([bounds isKindOfClass:[NSArray class]])
         parts = bounds;

@@ -94,7 +94,7 @@
 
 - (id)initWithMapBoxMarkerImage:(NSString *)symbolName tintColor:(UIColor *)color size:(RMMarkerMapBoxImageSize)size
 {
-    NSString *sizeString;
+    NSString *sizeString = nil;
     
     switch (size)
     {
@@ -112,7 +112,7 @@
             break;
     }
     
-    NSString *colorHex;
+    NSString *colorHex = nil;
     
     if (color)
     {
@@ -140,7 +140,7 @@
                                                (colorHex   ? [@"+" stringByAppendingString:[colorHex stringByReplacingOccurrencesOfString:@"#" withString:@""]] : @"+ff0000"),
                                                (useRetina  ? @"@2x" : @"")]];
 
-    UIImage *image;
+    UIImage *image = nil;
     
     NSString *cachePath = [NSString stringWithFormat:@"%@/%@", kCachesPath, [imageURL lastPathComponent]];