Must set SSL parameters before invoking sl_Listen

PUBLISHED_FROM=9147e7aa945f75e73d5c7cd7987cb5749025a86b

ev_timer_time may remain the same for legit reason, so to prevent looping, instead, reset it before invoking the handler.
To let user know what the initial setting was, pass it as the argument instead of current time (which is kind of pointless).

PUBLISHED_FROM=fa328009f097f9b49b5b0dd13a38ee6d6e6518de

PUBLISHED_FROM=2cb4449d2f36d59db2b0dc37c46b35de6a461810

PUBLISHED_FROM=92f43c7b0a705ff40c4aea07f2ee0627f8e0e4a1

PUBLISHED_FROM=d17e96a97e1621e9788844bcd627c3143d37315c

PUBLISHED_FROM=5202fa46a6a834bde35168ba566d3dce7c48f453

PUBLISHED_FROM=d20f138ae37c99a34cc29e7bfb327d7834404d93

PUBLISHED_FROM=05d3cca6223c963e7ae89dde3628fa8fad46e6bd

PUBLISHED_FROM=ebf5568abe82952ab2751298185a10189098013f

Now apps should use getters and setters instead of accessing struct
fields directly, e.g. instead of `get_cfg()->update.timeout` it should
be `mgos_sys_config_get_update_timeout()` to get the current value, and
`mgos_sys_config_set_update_timeout(123)` to update the value.

For now, the config structs are public, but they will be made private
soon, so use accessors to keep your code working.

PUBLISHED_FROM=f7d582421a8d7e4d1ed50a280f2670d8b62f8d45

Mongoose would report consumed bytes twice if mg_call is invoked recursively (e.g. proto_handler uses mg_call to invoke user's handler).
Reporting twice as much recved as was delivered effectively disables LwIP's TCP throttling and causes buffers to grow too big.

PUBLISHED_FROM=4ad5cd5db4dd54623bd6de2d50d32ddcc9e2b08a

PUBLISHED_FROM=a34cfa3ebc12daf75d7f24c8d3f3707dcc33d9a2

Mongoose 6.9

PUBLISHED_FROM=9e9047060b688291655ed227d19b7937fa9a147d

Mongoose 6.8

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

PUBLISHED_FROM=4ddfc25af77247fac7e7d04cc0e56d6f3800f87b

PUBLISHED_FROM=7bbe7dd20dca8435c786dca30200a4973ae0827d

PUBLISHED_FROM=07e820f539fa5feca2ad1cf81faca8404b773a65

PUBLISHED_FROM=b7325b38e881455df703b0b628c41931565ccb33

PUBLISHED_FROM=6f2d9849d75ca1ec2b6dade11ccad8d0c5d4b3bd

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

PUBLISHED_FROM=faaf5c50af31a0694c9308a664f2e418dbb0eb18

PUBLISHED_FROM=e16ee57bc30277e5b5684e53da78e69baaf9f779

PUBLISHED_FROM=263553121b992ec0f66b0275b4e10f4176281812

PUBLISHED_FROM=5831462c5be0b79afff32130a1f45784f32bc524

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

PUBLISHED_FROM=5e7fcc7bf145aa8e1045e8d627b1c0731bb4341b

Also, do not accept PUBLISH and SUBSCRIBE before a sucessful CONNECT.

PUBLISHED_FROM=b5096cdc2ec5da1358244c428efbbb2e20be1a05

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

https://forum.mongoose-os.com/discussion/comment/4620/#Comment_4620

PUBLISHED_FROM=679dd48e078615ef4f57d1879957b734f549ef2e

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

PUBLISHED_FROM=41ab3c5af0b1d07204619dd4d8dc2e84b6a54f32

PUBLISHED_FROM=73d6767e4aaa7249eeb5d76f9e7160be041292ca

PUBLISHED_FROM=62c73e5fb4f70e2b5b8824ce092012508640b173