if in packageCache
sg1
call .preload()
call .preload()
preloadPackage()
new ThemePackage
new Package

this.preload() call:
Does more than advertised here

.loadKeymaps()

Read from packagesCache:
If bundled package && in packagesCache

Read from file:
If !bundled || !in packagesCache

.loadMenus()
.activateCoreStartupServices()
.requireMainModule()
.loadSettings()
.activateKeymaps()
.activateMenus()
.preload()
.reigsterConfigSchemaFromMetadata()

initialize-application-window.js
Called right after global 'atom' is set

AtomEnvironment
.preloadPackages()

preloadPackages()