optimal implementation of caching logic

[vladgaidukov]

update logic for lazy loading files

[mrdoob]

Hmm... Why did you removed enabled?

[vladgaidukov]

I think that the cache must be enabled permanently. This will eliminate the possibility of performing repeated requests for file downloads.
If you think that there must be an option to disable the cache, I will add this, but I think that the default set it enabled. What do you think ?

[takahirox]

Refer to #6834

[vladgaidukov]

I added the ability to enable or disable the cache

[vladgaidukov]

Added the ability to enable or disable the cache

[looeee]

@vladgaidukov Just looking over this quickly - what improvements does it give over the current cache?

[vladgaidukov]

@looeee In the current implementation, the file is cached only after downloading it.
For example if you download 10 same files in the loop, there will be created 10 xhr requests.
In my implementation will be created only one xhr request and onload events for all 10 files will be called immediately after loading the first.

[Mugen87]

Solved via #12434