Use NSISOLatin1 encoding instead of ASCII

We used to fall back on the ASCII encoding if UTF-8 did not work out. However,
this causes its own problems; ASCII is only valid for the lower 7 bytes. We
solve this by using Latin-1, which should have a valid character for every
byte sequence

NSFileHandleExt.m

@@ -49,7 +49,7 @@
 				buffer[bytesReceived-1] = '\0';
 				NSString* s = [NSString stringWithCString: buffer encoding: NSUTF8StringEncoding];
 				if ([s length] == 0)
-					s = [NSString stringWithCString: buffer encoding: NSASCIIStringEncoding];
+					s = [NSString stringWithCString: buffer encoding: NSISOLatin1StringEncoding];
 				return s;
 			case '\r':
 				bytesReceived--;
@@ -59,7 +59,7 @@
 	buffer[bytesReceived-1] = '\0';
 	NSString *retVal = [NSString stringWithCString: buffer  encoding: NSUTF8StringEncoding];
 	if ([retVal length] == 0)
-		retVal = [NSString stringWithCString: buffer encoding: NSASCIIStringEncoding];
+		retVal = [NSString stringWithCString: buffer encoding: NSISOLatin1StringEncoding];
 	
 	free(buffer);
 	return retVal;

PBEasyPipe.m

@@ -76,7 +76,7 @@
 	NSData* data = [handle readDataToEndOfFile];
 	NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
 	if (!string)
-		string = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
+		string = [[NSString alloc] initWithData:data encoding:NSISOLatin1StringEncoding];
 	
 	// Strip trailing newline
 	if ([string hasSuffix:@"\n"])
@@ -101,7 +101,7 @@
 	NSData* data = [handle readDataToEndOfFile];
 	NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
 	if (!string)
-		string = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
+		string = [[NSString alloc] initWithData:data encoding:NSISOLatin1StringEncoding];
 	
 	// Strip trailing newline
 	if ([string hasSuffix:@"\n"])

PBGitTree.m

@@ -77,7 +77,11 @@
 		data = [handle readDataToEndOfFile];
 	}
 	
-	return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
+	NSString* string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
+	if (!string) {
+		string = [[NSString alloc] initWithData:data encoding:NSISOLatin1StringEncoding];
+	}
+	return string;
 }
 
 - (void) saveToFolder: (NSString *) dir