optimize suggestion for resources repeat requests

[Baldur404]

May be maintain a static pictures list 。If resources has already been requested,do not repeat send a new request to get the image.i find the edge/chrome browser (chromium kernel) does not optimize for repeating the same resource and still sends a request even this resource was been cached. The will send many many request ,even close to ten thousand requests when i load schematics about 30 of them.And i use firefox and safari did not find this issue.they are not send repeated request of image ,that face to same requset

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[JeanJPNM]

Related issue: #18.