Package TWiki::Configure::Load 
 Purpose 
This module consists of just a single subroutine 
readConfig.  It allows to
safely modify configuration variables 
for one single run without affecting
normal TWiki operation.
In normal TWiki operations as a web server this routine is called by the
BEGIN block of 
TWiki.pm.  However, when benchmarking/debugging it can be
replaced by custom code which sets the configuration hash.  To prevent us from
overriding the custom code again, we use an "unconfigurable" key
$cfg{ConfigurationFinished} as an indicator.
Note that this method is called by TWiki and configure, and 
only reads
TWiki.spec= to get defaults. Other spec files (those for extensions) are
not read.
The assumption is that 
configure will be run when an extension is installed,
and that will add the config values to 
LocalSite? .cfg, so no defaults are
needed. TWiki.spec is still read because so much of the core code doesn't
provide defaults, and it would be silly to have them in two places anyway.
 StaticMethod expandValue ($string) -> $boolean 
Expands references to TWiki configuration items which occur in the
value of other configuration items.  Use expand($hashref) if the item
is not a plain scalar.
Happens to return true if something has been expanded, though I don't
know whether you would want that.  The replacement is done in-place,
 StaticMethod readDefaults () -> \@errors 
This is only called by 
configure to initialise the TWiki config hash with
default values from the .spec files.
Normally all configuration values come from 
LocalSite? .cfg. However when
configure runs it has to get default values for config vars that have not
yet been saved to 
LocalSite.cfg.
Returns a reference to a list of the errors it saw.
SEE ALSO: TWiki::Configure::TWikiCfg::load