…, fix typos and make various improvements to the config file text and structure.

When run without --config the embedded copy of etc/rotonda.conf is used instead, and targets.proxy is removed if --proxy-destination is not supplied on the command line.

If --bgp-listen or --bmp-listen are supplied on the command line they override the BMP and BGP listen settings in the embedded config.

- Allow BGP peers to be missing.

  - Add missing semi-colon.
  - Filter out not in.

…nnections on a particular socket.

…age can link to the actual RIB query HTTP API rather than incorrectly assume a fixed path of /prefixes/.

…lt-mvp-config

…e-prefixes-query-link

…ined in roto scripts loaded from a roto script directory.

- Refactors roto script file reading from the units/targets to the Manager.

- Checks script loading, compilation and valid filter names at config load time instead of at filter execution time.

- Add MVP behaviour tests (WIP).

- Introduces a FilterName type.

…in case I return to this later.

…e required .roto files, e.g. if running from `cargo install`. Cleanup config initialisation and standard variable naming.

…ts_dir` dir `etc` doesn't exist.

This change had several knock on effects:
- Introduced RotoError::LoadError.
- Upgrade clap crate to fix bug with clap switcing help on own line or not even when disabled.
- Upgrade toml crate to fix inconsistent line breaks in diagnostic dump of post-processed config TOML.
- Adjust position handling in `Marked` due to changes in serde_spanned pulled in by other crate upgrades.
- Added new cmd line arg --print-config-and-exit and introduced `Terminated` for use in cases where `ExitError` wrongly limits us to just an error exit rather than a normal exit.
- Various minor tweaks to the clap config for improved read and usability.
- Log when exiting.

…gram

…ment to set the destination in MVP mode. Also make the MQTT unit consistent with the BMP proxy unit by having a destination setting rather than individual server_host and server_port settings.

…lue is.

…imply removing the Cargo feature entirely.

…ters.

… is supposed to use.

…of the no longer absent filtering within the BGP unit itself.

…hunking.

…ack fired on each VM exec that rejects the input (to enable easy counting of filtered out input messages), and remove support for metric types we don't need. Use the new callback to invoke the till now unused message_filtered() status reporter fn.

…ic now works.

…by bmp_tcp_in while this metric is based on BMP initiation messages received, so this is (a) misleading and (b) doesn't work anyway as when the sys name changes so can the router id and thus the changed metric would be in a different metric set, there'd be no effect on the previous metric.

…sequent BMP Initiation Message.

…and only remaining bmp-in metric. TODO: add a test showing bmp_in_num_invalid_bmp_messages increasing.

…ensure they are initialized on first use, otherwise metrics get lost.

…alid_bmp_messages counter to increase.

…ts manually during development.

…on to test the `bgp_tcp_in_connection_accepted_count` metric.

…using a mock BGP `Session`.

…uery-link

…uery-link

… whose APIs are linked to.

…ix-broken-metrics

…ater results may be different if called again.

… the BMP TCP input receiver on non-fatal errors (otherwise loss of the receiver causes the router read loop to abort anyway).

…ess verbose.