Replace fancy $$varname with actual varnames, to be nice to the IDE.
Docblock fix in CRM_Core_Config: type hint for $userSystem should be CRM_Utils_System_Base. TODO: Introduce an interface.
Add undeclared property CRM_Core_Config::\customPHPPathDir
Docblock and newline improvements in CRM_Core_Config and CRM_Utils_Hook. The IDE likes it.
Eliminate unnecessary local variable $userSystem.
Mark a possible bug in CRM_Utils_Hook.
Merge pull request #2504 from donquixote/donquixote

Docblock improvements and more in CRM_Core_Config and other classes.