Set push.default to current for backwards compatibility
Enable pop-up-windows and savehist-mode
Ignore some emacs files
Fix clash between em-smart and eshell-output-filter-functions

em-smart was previously being initialized lazily, so it would run
after customizations were applied and somehow set
eshell-output-filter-functions to nil. This commit makes it run
eagerly, which avoids the need for setting
eshell-output-filter-functions, because it gets set correctly by
em-smart.
In eshell, set EDITOR to emacsclient