[config] Moved functions from aucmd.vim to functions.vim

Change-Id: I876ef1b942ccd6025a7c01898299abf332c0eae8
[config] Removed color settings for menus

Let vim decides the color to be used

Change-Id: I611d7a416125915897880e79e9ba901734787771
[config] Re-enabled calendar plugin

Change-Id: I4956505d9d1bc9d6d7035b8e4b0712a32744baa1
[plugin] Added calendar plugin configuration

Configured date format and separator

Change-Id: I56b3883ece54a2190b484f75c488fb65ad0581db
[config] Updated Colour-Sampler-Pack repo name

Change-Id: I1fdfe4a6c6df41afc2288809c943f2f069c41778
[plugin] Change vim-airline theme manually

vim-airline theme is set manually, because the auto-detection did not work with
summerfruit256 theme

Change-Id: Iffa4688cbdbcb90818f843dc94ae1d54c6d524b5
[plugin] Changed startify fonto color to fit the summerfruit256 theme

Change-Id: I902c2f238c4d7b78968a194b7ff1daca6f134391