CL: Mongoose Web Server: Digest authentication: Fix nonce validity check (expired nonce or nonce from the future did not cause the the check to fail)
CL: Mongoose Web Server: Digest authentication: Fix nonce request value; it worked before because nonce validity check was broken as well
CL: Mongoose Web Server: Digest authentication: Add `nonce` argument to `mg_http_create_digest_auth_header()`: clients should use the value received from the server's authentication request.

Resolves https://github.com/cesanta/mongoose/issues/809

PUBLISHED_FROM=5e59f90ed6b2a4311ed6763159da81c2aaf6af4c

CL: Mongoose Web Server: Websocket: Respond to Ping with Pong
CL: Mongoose Web Server: Websocket: Properly close a connection with Close frame (in response to a client's close and when protocol failure is detected)
CL: Mongoose Web Server: Websocket: Fix support of fragmented messages
CL: Mongoose Web Server: Websocket: Add support for control frames interjected in the middle of a fragmented message

PUBLISHED_FROM=e2b3794aaacc64633540c493194cccc62afa2077

Fixes https://github.com/cesanta/mjs/issues/82
Integrates https://github.com/cesanta/mjs/pull/85

PUBLISHED_FROM=2f5f50c25ec1c92fdfb783cd95cb57f0cb20642b

CL: Fix OOB access in mg_match_prefix_n().
    Made mg_match_prefix_n() return non-negative result.

PUBLISHED_FROM=611454df6a6c55bfa7ddf05e7d268a86fa0457a8

AWS MQTT connection works

Also fixes https://github.com/mongoose-os-libs/ethernet/issues/1 (because why not).

PUBLISHED_FROM=7b0fa8894f2127335d075f2a97fcd37b932006b2

Standardize common packages in build images, to make better use of Docker image cache.

PUBLISHED_FROM=a080e83cf5dd80feaf7960147dee36413244a92c

PUBLISHED_FROM=de02f5cc6a9d854e92cf674e5382f793709da831

PUBLISHED_FROM=0a321ace3753a518e299b795fb7a4eed19708bb6

PUBLISHED_FROM=3b75fd8247ba9028e0ef0c3e211e7c1a80013951

PUBLISHED_FROM=2c176091ffb6c7c5cfe8ea4f05b6109e00b33383

PUBLISHED_FROM=1bfc6e332f56b68eb6155bb729a97a0d8d5a316c

To avoid name clashes.

PUBLISHED_FROM=e6ae32ec48f9b599eace7a9214a1863cdc185fd9

PUBLISHED_FROM=b85fe1ee1e7bae4528c1240d8531c410728d0709

PUBLISHED_FROM=7cde8b374d5e318b5cdd69fc5b4de86b2a9552f5

PUBLISHED_FROM=c61fa89018f8cef4f798e094acff8d36c72869f2

Must set SSL parameters before invoking sl_Listen

PUBLISHED_FROM=9147e7aa945f75e73d5c7cd7987cb5749025a86b

PUBLISHED_FROM=d17e96a97e1621e9788844bcd627c3143d37315c

PUBLISHED_FROM=5202fa46a6a834bde35168ba566d3dce7c48f453

PUBLISHED_FROM=05d3cca6223c963e7ae89dde3628fa8fad46e6bd

PUBLISHED_FROM=9e9047060b688291655ed227d19b7937fa9a147d

PUBLISHED_FROM=082d0bf5e9b06b850382ce502c7f5b4d68a6a328

Which is a slightly modified version from
https://stackoverflow.com/questions/283166/easy-way-to-convert-a-struct-tm-expressed-in-utc-to-time-t-type

PUBLISHED_FROM=b73f920ca42c45473c23337782e815306bdf69f1

Add checks on the number of subscribe requests per packet and overall per-session subscription limit.

PUBLISHED_FROM=faaf5c50af31a0694c9308a664f2e418dbb0eb18

PUBLISHED_FROM=db89a45a536f0234d6d5cf740354c0dbeeff1f26

```
Using port /dev/ttyACM0
[Aug 30 19:33:02.105]
[Aug 30 19:33:02.114] cc32xx_init          c_no_libs 1.0 (20170830-163205/mos8@6587ffd6+)
[Aug 30 19:33:02.123] cc32xx_init          Mongoose OS 2017083016 (20170830-163205/mos8@6587ffd6+)
[Aug 30 19:33:02.130] cc32xx_init          RAM: 253588 total, 240044 free
[Aug 30 19:33:04.430] cc32xx_start_nwp     NWP v3.4.0.0 started, host driver v2.0.1.19
[Aug 30 19:33:04.437] mgos_vfs_dev_open    slfs_container ({"prefix": "spiffs.img.0"}) -> 20005a64
[Aug 30 19:33:04.450] cc32xx_vfs_dev_slfs_ 20005a64 spiffs.img.0.0 262144 0xfffffffffffffffe
[Aug 30 19:33:04.457] mgos_vfs_mount       Mount SPIFFS @ / (dev 20005a64, opts ) -> 20005a74
[Aug 30 19:33:06.102] mgos_vfs_mount       /: size 233681, used: 4016, free: 229665
[Aug 30 19:33:06.108] mgos_vfs_mount       Mount SLFS @ /slfs (dev 0, opts ) -> 20005ed4
[Aug 30 19:33:06.114] mgos_vfs_mount       /slfs: size 0, used: 0, free: 0
[Aug 30 19:33:06.718] mgos_sys_config_init MAC: 04A316459442
[Aug 30 19:33:06.720] mgos_sys_config_init WDT: 30 seconds
[Aug 30 19:33:06.724] Hello, world!
[Aug 30 19:33:06.728] mgos_init            Init done, RAM: 253588 total, 236544 free, 235864 min free
```

PUBLISHED_FROM=7e83c9ddcc642bd324a40e125d6636ece824fb18

For now, we only support SPIFFS-in-a-box, same as CC3200.
On CC3200SF it should be possible to have SPIFFS on built-in flash, but that is left for later.

PUBLISHED_FROM=dee337c8cd8ed288c22abe9960eef81e6e90cc4a

Also make CC3200 use newer ARM compiler, generates slightly smaller code.

PUBLISHED_FROM=a0be49d7ea864a95886f7110887a59f6f11802d7

And mgos_conf_check_access_n()

PUBLISHED_FROM=c7de937b4f5463ca463d604183a4ee831617bd6d

Achievement unlocked: CC3220 port prints a boot banner.
Then locks up.

Included in this PR is refactoring to pull out common parts to be shared with CC3200.

PUBLISHED_FROM=5fb9d9a00bb9ce7f63dde20bc1876076b76d5257

Fixed bug in websocket handshake:
now adding Sec-WebSocket-Protocol header in handshake response.

PUBLISHED_FROM=e4a71ff9dc4aeec63db40cb7f356dc5b25c1215a

PUBLISHED_FROM=f97569ae2f31ab94ce4875eae4d0a198f719c388

Ignore all the mess, this is just the beginning...

PUBLISHED_FROM=41ab3c5af0b1d07204619dd4d8dc2e84b6a54f32

PUBLISHED_FROM=62c73e5fb4f70e2b5b8824ce092012508640b173

Fix headers that didn't have it

PUBLISHED_FROM=ce8140783d4b661f16278a4a5adc957b21965473

Change the API to heap-allocate the string and get rid of a bunch of fat stack buffers.

PUBLISHED_FROM=c793dc64a9a044a9769d92ea16859f5d704a2181

PUBLISHED_FROM=4306e870e2cab854febb6becc198ca2247e2e002

Write unit tests for some mg_str functions.

PUBLISHED_FROM=1fc7e1d5d5ef259d4023f295aec8651caa3e7e86

PUBLISHED_FROM=1803e726eee7bb64496d70389655083eb70257ab

PUBLISHED_FROM=efa9cc3aaf0c5ae8841e029370f882b615cebf1b

PUBLISHED_FROM=e69e298a51dbe0f9c47184169ecad06eef0676fc