CL: mos support for LFS (littlefs) https://github.com/ARMmbed/littlefs

PUBLISHED_FROM=e72957b4fb2c78949af4cf6d5bfef135ddba9fd9

Set CLOSE_IMMEDIATELY flag when destroying conn.
This avoid some races in LWIP adapter.

CL: mg_lwip: Fix race during clean conenction teardown

PUBLISHED_FROM=5c67982390dfaf83527e85d1291f64c6050aa932

startup cleanup on CC3220

CL: none

PUBLISHED_FROM=0998fad82fbcdbde30dca42833f2e48d148592bf

PUBLISHED_FROM=9997c64ed0c713b5b8b29df7a49b532e880eac53

CL: Fix TZ on ESP8266

PUBLISHED_FROM=435a501a8b52524bccb67bb5a8ae7e09dfb4d44a

Enables extra compile-time checks

CL: none

PUBLISHED_FROM=9f7d658fbda5c721cf40293bf29967bb056d0437

Also remove `-O3` optimization flasg, it negates `-Os`. Saves ~400 bytes.

CL: none

PUBLISHED_FROM=f40f42e4f54a8e0e003ab65ec8f5838c2d932876

CL: Apache license to common/

PUBLISHED_FROM=901e9e4b12a31289b3515d1f86dd56a7f0f35c5e

A major cleanup, disentangling net_if and ssl_if.
Pulled a lot of common logic into the core and reduced size of net_if implementations.

CL: Mongoose net_if and ssl_if refactoring

PUBLISHED_FROM=29bd4dcb264a1fd96b3dd164e2d880e1c2c0921e

In preparation for making moving to lib.
Reduce amount of makefile copypasta a bit.

CL: none

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PUBLISHED_FROM=9a81cc34aa0039a75c851bc3685055f46936252e

E.g. if `ASSERT_EQ(myfunc(), 123)` fails, `myfunc()` would be invoked again to print the actual value.
This can cause confusion sometimes.
To avoid this, we cast arguments to double, which is wide enough for most cases and we provide a variant for 64 bit value types for when it's not.
We also perform a check and fail if argument to the check results in loss of precision.

CL: none

PUBLISHED_FROM=a14551289d92e8a5dead21d16471ebddebe938a8

CL: none

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PUBLISHED_FROM=d52aea1648ed8ec8dd2e71168884795d995b1826

CL: none

PUBLISHED_FROM=ee76407d89f3fcbe3da23810117a374d06af0a25

To properly fail a test in a subroutine, return value needs to be passed up.
This snippet makes it short.

PUBLISHED_FROM=2f6328b5eb2921a4caa53d8887c02f73a5d817ea

PUBLISHED_FROM=3cd6dd7f04b650ca637788d1017b6b5146c79569

PUBLISHED_FROM=78acb18d597b6f47f31da13087fa6685f21ce445