Extended Haskell syntax highlighting for vim

Vim's built-in syntax highlighting for Haskell was kind of lackluster,
so this commit adds the hasksyn plugin.
Syntax highlighting for RPAL

RPAL is a programming language used in COP5555: Programming Language
Principles at the University of Florida. This commit adds the syntax
highlighting plugin for vim that I wrote for RPAL.
Enable git log's "decorate" option

The decorate option shows what tags are associated with what commit,
what HEAD points to, and more.