This reverts commit 2bb6f135.

Changed Yii autoloader to support loading PSR-4 classes only (i.e. PEAR-styled classes not supported anymore)

code style section has been added here:
https://github.com/yiisoft/yii2/wiki/Core-framework-code-style#self-vs-static

verification code for properties:
https://gist.github.com/cebe/7566916

Control statements based on the if and elseif constructs must have a single space before the opening parenthesis of the conditional and a single space after the closing parenthesis.

See discussion about exceptions in autoloader here:
https://groups.google.com/forum/?fromgroups#!topic/php-fig/kRTVRSIJ0qE

helps reducing weird error messages.

autoload return value has no effect on other autoloaders
they will only be called based on whether the class has been loaded or
not.