[breaking] lang/java: rewrite & new submodules #157

Split into two submodules: +eclim & +meghanada. These must be explicitly
included in lang/java's module flags in init.el.

modules/lang/java/packages.el

@@ -1,7 +1,14 @@
 ;; -*- no-byte-compile: t; -*-
 ;;; lang/java/packages.el
 
-(package! meghanada)
 (package! android-mode)
 (package! groovy-mode)
 
+(when (featurep! +meghanada)
+  (package! meghanada))
+
+(when (featurep! +eclim)
+  (package! eclim)
+  (when (featurep! :completion company)
+    (package! company-emacs-eclim)))
+