Release v2.6.14 is out: generic CIP PLC and new attributes

[Kyle]

There are a fair number of small things in this release.

1. EIP Network Scanner
   - Added new scan_eip_network program to test UDP support and some internal new network code.
   - Tests UDP broadcast and coroutine networking.
   - Just prints out the fields from the List Identity response.

2. Connection Inactivity Timeout Feature
   - New attribute for session/connection/device management, connection_inactivity_timeout_ms
   - Can get/set new attribute.  Clamped at maximum of about 30 seconds.  Clamped at minimum of 100ms.
   - Can be changed at runtime
   - Added tests for idle timeout behavior to the CI and real hardware tests.
   - The value defaults to the maximum possible

3. Connection Status Attribute
   - Added connection_status attribute.   Only get, no set.  All PLC types.
      - PLCTAG_CONN_STATUS_UP = 0 -- Connected and ready for operations
      - PLCTAG_CONN_STATUS_DOWN = 1 -- Not connected
      - PLCTAG_CONN_STATUS_DISCONNECTING = 2 -- In process of disconnecting
      - PLCTAG_CONN_STATUS_CONNECTING = 3 -- In process of connecting
      - PLCTAG_CONN_STATUS_IDLE_WAIT = 4 -- Waiting to reconnect after idle disconnect
      - PLCTAG_CONN_STATUS_ERR_WAIT = 5 -- Waiting to reconnect after error
   - Added idle timeout tests to CI and real hardware tests.

5. Generic CIP PLC Support - New PLC type for identity support
   - Added the generic CIP PLC with @identity tag type support
   - Will be slowly adding internal code to allow use of generic on any CIP/EtherNet IP PLC so that the system will automatically configure for the correct PLC type.  Paths are still an issue.
   - get_identity tool added.
   - Identity support added to tag_rw2.

6. Changed default EtherNet/IP timeout to 30 seconds This is a change from existing behavior!  Please let me know if this breaks anything.  This timeout is changed in the negotiation with the PLC for Control/Compact Logix, Micro800 and Omron.  Not for PCCC/DF1 PLCs.  Changed for Modbus too but only on the client side as Modbus does not have a timeout on the server side.

7. User @DennisKriete contributed a PR to change when the libplctag.pc file was generated so that it shows up earlier.  Thanks!

You can get this release here.

Best,

Kyle