Add support for scoped defaults in config schemas
Upgrade to underscore-plus 1.6
Accept escaped dots in config settings keys 

Fixes #3898
Add new ScopeDescriptor object
Return ScopeDescriptor objects
Update descriptor docs
ScopeDescriptor::create -> fromObject
Fix specs
:arrow_up: atom-shell@0.18.2
Log a warning if a package has an incompatible main module

I’ve been tripped up by this twice now, so it would be good to provide
some feedback when it happens.
Merge pull request #3915 from atom/atom-shell-v0.18.2

Upgrade to atom-shell@0.18.2
Add setActiveTemplate helper
Close the template

Menu.buildFromTemplate modifies it so copy before hand
so it can be reused
Store each window's menu template

Restore it when the window gains focus
Compare templates before swapping them out
:memo: Add template
Merge pull request #3906 from atom/ks-change-menu-on-focus

Swap out application menus on focus
Load extensions in ModuleCache.create
Enable extensions for installed packages
Merge pull request #3909 from atom/ks-extension-cache-for-packages

Add extension cache for installed packages