Cater for deleted logic: files, classes, functions and methods

[bobbingwide]

Some plugins remove logic between versions.
Some plugins deprecate functions, others simply remove them.
oik-shortcodes needs to cater for deletions of

• files
• classes
• functions
• methods

and possibly

• hooks
• shortcodes

Example.
The class Jetpack_VideoPress_Shortcode was in jetpack/modules/videopress/shortcode.php in v3.9.6.

The class no longer exists in the latest version ( 4.0.4 ); it was removed by changes in Automattic/jetpack@ba4af49

[bobbingwide]

Note: The parser for the official WordPress Reference caters for deletions. Perhaps it's time to spend more time on this solution.

[bobbingwide]

In my first attempt at logic that will completely delete the API reference before rebuilding, I left a few oik_parsed_source records in the database.

These should be tidied by modifying set_md5_hash.php to delete any oik_parsed_source record that refers to a post, via oik_sourceref, that is no longer present.

This is not particularly important since it was only for one plugin in a test system.