This adds a command history, both for the CLI as well as for
commands sent by the web-interface. They are written to a ring buffer
in order to work safely with a relatively small amount of RAM
The buffer is used to read the current in-RAM configuration
from the switch by the web-interface. It could also be used
to implement cmd history via cursor up/down in the CLI.
This removes the limitation that a file served from FLASH memory
needs to be smaller than the TCP buffer size. Now we serve up to
the TCP buffer size in the first go and then remember what parts
still need to be sent. As soon as the previous package has been
acked, the next chunk of data is copied from flash into the
TCP transmit buffer and gets sent. We take care only to send
the current TCP window size so no further fragmentation needs to
happen, thus optimizing transmission of the remainder.
The Makefile has the version number and generates a version.h which
has VERSION_SW define that looks like "v<VERSION>-g<GIT_SHORT_HASH>".
Software version shows at boot in the serial console.
And shown with command: `version`.
It can also be requested via `information.json`.
```
{
"ip_address": "192.168.10.247",
"ip_gateway": "192.168.10.1",
"ip_netmask": "255.255.255.0",
"mac_address": "1c:2a:a3:23:00:02",
"sw_ver": "v0.1.0-gd48235f",
"hw_ver": "SWGT024-V2.0"
}
```
Remove all the extra spaces from the json.
Also simplify the generation of the json.
Codespace is cheap so duplicated strings is not an issue.
But generating strings from different parts is more expensive in clock cycles.
Add a helper funcion `bool_to_html()` to generate bool value for html output.