Evaluate package! properties & error on :fetcher

- No longer translates :fetcher to :host. Update your package!
  declaration people!
- Now evaluates the values for properties (except for :recipe IF it is a
  list whose CAR passes keywordp -- for backwards compatibility).
- Throws error if an invalid property is used for a package!'s :recipe

core/autoload/packages.el

@@ -81,7 +81,7 @@
 
 Excludes packages that have a non-nil :built-in property."
   (when-let (plist (doom-package-get package))
-    (not (plist-get plist :ignore) t)))
+    (not (plist-get plist :ignore))))
 
 ;;;###autoload
 (defun doom-package-private-p (package)