Fixes #2629: `Module::controllerPath` is now read only, and all controller classes must be namespaced under `Module::controllerNamespace`

Changed `Controller::afterAction()`, `Module::afterAction()` and `ActionFilter::afterAction()` to pass `$result` by value instead of reference

Revert "Added `yii\base\Module::getParam($name, $defaultValue = null)`  to conveniently work with application parameters"

This reverts commit 3b95aa9c.

Added `yii\base\Module::getParam($name, $defaultValue = null)`  to conveniently work with application parameters

fixes #1541

Moved Application::$controllerNamespace init into variable declaration, reordered Module::__construct.

This reverts commit 6b15768a.

- cleanup API and usage, add documetation link
- introduced @property feature in getter or setter which has precedence
  over @return or @param tag if present