Added userData to allow user to store context variable.

[valkuc]

cgiData cannot be used for this purpose in templates (because it's used internally), new userData can - it's dedicated for this.

[valkuc]

Example usage:

void ICACHE_FLASH_ATTR cgi_device_manage_tpl(HttpdConnData *connData, char *token, void **arg)
{
	char buf[128];

	manage_state_t *state = connData->userData;

	if (token == NULL)
	{
		// called at the end of template processing
		if (state != NULL) os_free(state);
		return;
	}

	if (state == NULL)
	{
		state = os_malloc(sizeof(manage_state_t));
		if (state == NULL)
		{
			LOGN(LOG_ERR, "Can't allocate state struct.");
			return;
		}
		os_memset(state, 0, sizeof(manage_state_t));

		int len = httpdFindArg(connData->getArgs, "id", buf, sizeof(buf));
		if (len > 0)
		{
			state->id = atoi(buf);
			//Read state->dev from some storage
		}
		else
		{
			state->dev.active = true;

			//Fill other state->dev fields here
		}

		connData->userData = state;
	}

	if (os_strcmp(token, "foo") == 0)
	{
		os_strcpy(buf, "bar");
	}
	else if (os_strcmp(token, "bar") == 0)
	{
		os_strcpy(buf, "foo");
	}
	//
	// more if else blocks
	//
	else
	{
		os_strcpy(buf, "");
	}

	httpdSend(connData, buf, -1);
}