Add examples, simplify sections and ordering of topics.

Inside function that gets called during debugging, it gets in the way
pretty fast.

Hopefully this is ledd confusing than calling 'toes' something that
represents most of the original string

This seems too hard to support safely, and the advantages are minimal as
most cases will be possile to solve by wrapping the builtin into a
function.

Turns out that get_version and release.sh strategy do not agree
very well on this, which may end up as version comparison problem.

SemVer 2.0 says that pre-release versions go before the associated
versions, that is, 1.0.0-blah goes before 1.0.0, and at the same time
remove the compatibility guarantee.  This means that if pre-releases
are needed, we will probably need to change both PRERELEASE and VERSION,
which is not what was expected when writing release.sh.

For now, the safe thing is to remove PRERELEASE altogether.  If we ever
need to do a pre-release, we will re-verify if it works properly; until
then, build meta-data give us enough luxury.

The caching does not clean up, and is mostly unnecessary since Linux
will cache the file anyway.

Reserve PROJNAME for a "human-readable" name.

Colon in STAGE will most probably confuse matcher and lead to corrupt
version data.

This should give better hint if built from a feature branch

For now the spelling has been decided "Fastfoo", not "Fast Foo", or
"FastFoo".

These have been moved to saturnin

The tool is mostly based on ini files; make this more obvious.

The version based on config.mk has been finalized to include more
features:

 *  Build variables are now defined in config.ini.
 *  The ini system can self-reference other keys (up to several levels).
 *  Some config (namely `ENV` section) can be overrided by environment
    variables.
 *  The installer is now more portable (ported to saturnin so far):
    everything can be defined in config.ini