Environment: DI container class is named EnvironmentContainer instead of SystemContainer

It prevents "Compile Error: Cannot redeclare class SystemContainer" when another container is later created by Configurator, and shows correct error "SystemContainer has already been created automatically by Nette\Environment"
LimitedScope: removed workaround for bug #48912 in PHP 5.3.0
removed usage of Nette\Utils\LimitedScope (except Templating)
removed usage of constant NETTE_DIR
AutoLoader: removed $count (and fixed NetteLoader test)