* New "general-purpose" datastore upgrade callback added which i called once on startup, intended for lo

w-level general upgrades and as a complement to module-specific upgrade.
  * Called on startup after initial XML parsing, but before module-specific upgrades
  * Enabled by definign the `.ca_datastore_upgrade`
  * [General-purpose upgrade documentation](https://clixon-docs.readthedocs.io/en/latest/backend.html#ge
neral-purpose)
* JSON parse error messages change from ` on line x: syntax error,..` to `json_parse: line x: syntax err
or`
* Unknown-element error message is more descriptive, eg from `namespace is: urn:example:clixon` to: `Fai
led to find YANG spec of XML node: x with parent: xp in namespace urn:example:clixon`.
* C-API parse and validation API more capable
  * `xml_spec_populate` family of functions extended with three-value return values
    * -1: error, 0: parse OK, 1: parse and YANG binding OK.
  * `xml_parse` and `json_parse` API changes
    * Three value returns: -1: error, 0: parse OK, 1: parse and YANG binding OK.
    * Extended `xml_parse_file2` and `xml_parse_string2` extended API functions with all options available.
      * New concept called `yang_bind` that defines how XML symbols are bound to YANG after parsing
    * Existing API same except `xml_parse_file` `endtag` argument moved to `xml_parse_file2`
* C-API: Added instrumentation: `xml_size` and `xml_stats_get`.
* Fixed: Enabling modstate (CLICON_XMLDB_MODSTATE), changing a revision on a yang, and restarting made the backend daemon exit at start (thanks Matt)
  * Also: ensure to load `ietf-yang-library.yang ` if CLICON_XMLDB_MODSTATE is set

test/test_netconf_whitespace.sh

@@ -57,8 +57,7 @@ module whitespace{
 }
 EOF
 
-
-new "test params: -f $cfg"
+new "test params: -f $cfg -s startup"
 
 echo '<config><ex:x xmlns:ex="urn:example:whitespace">    
  <ex:y>   <ex:a>foo</ex:a>\n  <ex:b>  </ex:b></ex:y>   </ex:x></config></edit-config></rpc>]]>]]>$start</config>' > $dir/startup_db