Increase socket buffer size to the maximum WINC1500 transfer size

[sandeepmistry]

This resolves arduino-libraries/ArduinoHttpClient#14 for me - still need to understand why.

cc/ @creends

[sandeepmistry]

The regression in arduino-libraries/ArduinoHttpClient#14 was introduced by #91 (the fix for #86).

On non-AVR boards, SOCKET_BUFFER_MTU and SOCKET_BUFFER_TCP_SIZE are both set to 1400. With the current code the WINC1500 sends a 1400 byte chunk of data, then the next 46 bytes. After this 258 bytes come in, however since the full flag is not set, it overwrites the data at index 0 (same index of the previous 46 bytes), and causes the buffer to become corrupt.

Alternatives to the changes proposed in this PR:

1. Revert the changes from Do not set full flag if remaining size if 0 #91, but this will re-introduce WiFi.status() == WL_CONNECTED although connection lost and WiFi.RSSI() == 0 #86.

or

2. Change SOCKET_BUFFER_MTU to 1446 and make SOCKET_BUFFER_TCP_SIZE 723. Will still probably re-introduce WiFi.status() == WL_CONNECTED although connection lost and WiFi.RSSI() == 0 #86.

[sandeepmistry]

From @creends in arduino-libraries/ArduinoHttpClient#14 (comment)

So #116 works fine for me too.
No more unwanted characters at the end of the answers, and whole responses for the longer ones.
Thank you for your help.

Great, thanks for trying it out! I think we can merge this and tag a new release ...

@akash73 @agdl what do you think? It also solves #115 for me.

[akash73]

LGTM, nice.
@agdl , if it's ok to you, pls merge.