Only set omnifunc and completefunc when empty
updated for version 7.3.798
Problem:    MzScheme: circular list does not work correctly.
Solution:   Separate Mac-specific code from generic code. (Sergey Khorev)
Added tag v7-3-798 for changeset cdaa688e3ddd
Merge branch 'master' into vim-clojure-static

* master:
  Added tag v7-3-798 for changeset cdaa688e3ddd
  updated for version 7.3.798 Problem:    MzScheme: circular list does not work correctly. Solution:   Separate Mac-specific code from generic code. (Sergey Khorev)
Update clojure runtime files

* Update keywords to Clojure 1.5.0-RC6
* Refactoring for integration with external rainbow paren scripts
* Replace contains=clojureTopCluster with contains=TOP