Added the method Configuration::Add

This methos should allow loading configuration entries as n array
instead of parsing from file.
Migrated global configuration to new loading scheme

global configuration will now be loaded by Configuration::Add
Migrated access control configuration to new scheme

Ditto as global configuration
Configuration::Add will now correctly dispatch

Callbacks waiting on categories loaded via Configuration::Add will now
be called as expected.
Migrated PHPMailer configuration to new scheme

Ditto
Removed Configuration::Load

Configuration will no longer be loaded by parsing files
Configuration no longer needs INI
"polyfills" for array_replace and *_recursive

array_replace_recursive and array_replace backoported for old PHP
versions
Configuration will use array_replace_recursive
Removed Configuration::FieldExists (not used)
"fix" for default configuration
Configuration callback dispatch fix
"fix" for AccessControl default configuration
Restructured database configuration scheme
Improved query and wildcard support
Merge remote-tracking branch 'origin/develop'