Added support for two new standard errors: EnvironmentError and OSError.  The EnvironmentError serves primarily as the (common implementation) base class for IOError and OSError.  OSError is used by posixmodule.c
Added support for two new standard errors: EnvironmentError and
OSError.  The EnvironmentError serves primarily as the (common
implementation) base class for IOError and OSError.  OSError is used
by posixmodule.c

Also added tuple definition of EnvironmentError when using string
based exceptions.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator