Allow continue on download retries

[mildlyhuman]

This patch tries to resolve https://github.com/Gictorbit/photoshopCClinux/issues/175 , https://github.com/Gictorbit/photoshopCClinux/issues/167 , https://github.com/Gictorbit/photoshopCClinux/issues/150 (and alikes if they exist). The server (victor.poshtiban.io) drops connection(?) every 200Mb or so, making curl to fail with "HTTP/2 stream 0 was not closed cleanly: INTERNAL_ERROR (err 2)".

Existing suggestions either need custom script, or at least require the user to download and move the file. It seems unnecessary. I propose to retry & continue in-place with wget, which should be available on most linux systems.

The curl command was also modified to allow retry and continue, but it won't go through that particular error. I'm not familiar with curl, sorry. I think it should be able to, but can't find the right solution.

[mildlyhuman]

To be fair with curl, I have not tested aria2 (thus the no edit). Maybe the curl command can benefit from a little warning message, if the file download link continue to be not very stable.

Anyway, I just want to propose the allow-continue behavior since it's readily available in at least wget.

[bpavuk]

And because of this you must opt out of curl

[ZeloBox]

This solution is fixing this bug. I succesfully downloaded photoshopCC-V19.1.6-2018x64.tgz from https://victor.poshtiban.io/p/gictor/photoshopCC/photoshopCC-V19.1.6-2018x64.tgz now Download limit at site victor is 50 Mb now.