Refactor Project API to reflect changes upstream

projectile-project-root no longer returns `default-directory` if not in
a project (it returns nil). As such, doom-project-* functions (and their
uses) have been refactored.

+ doom-project-p & doom-project-root are aliases for
  projectile-project-p & projectile-project-root.
+ doom-project-{p,root,name,expand} now has a DIR argument (for
  consistency, since projectile-project-name and
  projectile-project-expand do not).
+ The nocache parameter is no longer necessary, as projectile's caching
  behavior is now more sane.
+ Removed some projectile advice/hacks that are no longer necessary.
+ Updated unit tests

modules/lang/cc/autoload.el

@@ -104,7 +104,7 @@ preceded by the opening brace or a comma (disregarding whitespace in between)."
              (executable-find "rc"))
     (with-temp-buffer
       (message "Reloaded compile commands for rtags daemon")
-      (rtags-call-rc :silent t "-J" (doom-project-root))))
+      (rtags-call-rc :silent t "-J" (or (doom-project-root) default-directory))))
   ;; then irony
   (when (and (featurep 'irony) irony-mode)
     (+cc|irony-init-compile-options)))