Add syntax highlighting for glsl

vimrc

@@ -23,6 +23,7 @@
 "| Tagbar           | https://github.com/majutsushi/tagbar            |"
 "| Undotree         | https://github.com/mbbill/undotree              |"
 "| Vim-Airline      | https://github.com/bling/vim-airline            |"
+"| Vim-GLSL         | https://github.com/tikhomirov/vim-glsl          |"
 "| Vim-Gnupg        | https://github.com/jamessan/vim-gnupg           |"
 "| Vim-Perl         | https://github.com/vim-perl/vim-perl            |"
 "| Vim-Startify     | https://github.com/mhinz/vim-startify           |"
@@ -78,6 +79,7 @@ if has("unix") || has("mac")
         Plugin 'vim-airline/vim-airline-themes'
         Plugin 'vim-airline/vim-airline'
         Plugin 'godlygeek/tabular'
+        Plugin 'tikhomirov/vim-glsl'
         Plugin 'jamessan/vim-gnupg'
         Plugin 'kien/ctrlp.vim'
         Plugin 'Lokaltog/vim-easymotion'