fix missing standard includes

These were a problem only if arch.h does not include them.

Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>

Fix no newline at end of http_client.c

http_client.c: Fix compile when TCP is disabled

http_client: fix compiling if mem_size_t is smaller than size_t

http_client: call tcp_recved for header bytes

Without this, closing the connection after successful transfer resulted
in a RST being sent because the window was not fully marked as 'recved'.

Signed-off-by: goldsimon <goldsimon@gmx.de>

various IPv6-only compile fixes

http_client: check current state when receiving FIN

fix compiling http_client and altcp_proxyconnect with gcc

http_client: change user-agent and make it overridable

altcp: simplify creating different types by adding an allocator concept

This is done with an example in the http_client

Signed-off-by: goldsimon <goldsimon@gmx.de>

Add HTTP client to documentation

http_client: httpc_tcp_recv did not return inner_conn's recv return value

Signed-off-by: goldsimon <goldsimon@gmx.de>
Reported-by: Our Air Quality <info@ourairquality.org>

http client: add https support, fix parsing header with chained pbufs

http client: fix proxy support

apps: add http client

Signed-off-by: goldsimon <goldsimon@gmx.de>