Add ability to use the prefetcher with a custom image manager

[tfonfara]

Hi,

it would be great if you could change the SDWebImagePrefetcher init method in a way, that we could use the prefetcher with a custom image manager (compare with #1041)

- (id)init {
    if ((self = [super init])) {
        _manager = [self createImageManager];
       ...
    }
    return self;
}

- (SDWebImageManager *)createImageManager {
    return [SDWebImageManager new];
}

Thank you,
Tobias

[mythodeia]

@tfonfara can this be of any assistance

[tfonfara]

@mythodeia this is exactly what I'm looking for, but unfortunately it isn't merged yet

[mythodeia]

until its merged you can copy paste the code you need
luckily its not that big of a change

[tfonfara]

Thanks, I've already included the snippet from my 1st post :)
I'll close the issue.