V11

2022/05/18 V11 :
> fix issue " Still some CRC errors occur when uploading on SDCard #21 ": remove sevbuf use to fix the last CRC errors and limit
to only 1 transfer for sdCard operations (simultaneous transfers leads in CRC errors)
> multi transfer enhancement : reduce open/close connection time with
- using a static preallocated array of threads (before it was allocated statically when creating the connection)
- manually set cpu and priority of transfer threads
> now use also a small buffer for UL operations (before setting manually CPU and priority, a large buffer was used to let other
connections start)
> tweak the buffers sizes used for DL / UL
Use 25% DL vs 75% UL of the reserved memory for buffer socket operations (instead of 50/50)
> This last setting increase DL speeds obtain when multi-transferring. Using a small buffer for upload reduced the "speed displayed"
on UL operation (now take the fwrite time into account).
This version gives max speeds over 4M/s on both ways and treat a large number of files more quickly.