Single underscore will be used for not-so-hidden names.

For purpose of rewriting user's INI, we don't want to mess it up more
than is necessary.

Drop the unnecessary and space-wasting requirement that `do` and `then`
must be alone on line.  It's a thing of the past!

Decouple variable declarations so that each can have docstring.
In case of _relck() we also rename variable $relsrc to a more
context-specific term $oracle.

Where not required, they only add visual cruft.

Too verbose; makes it hard to read the rest.

Some parts got a bit confusing over time, also there was repetition.

In this commit:

 *  the release fact gathering routines have been moved to separate
    module,

 *  some less useful routines have been removed,

 *  some internal interfaces have been changed to allow for more
    readable code.