small change on syntax colors nothing interesting
ADD: Two level sort function

This commit add the first interesting difference from freitass original
version. It provides a two level sort function which allow the user to sort
the todo by project (or context) then by priority.

TODO: Maybe think about three level sort (project, context, priority) in any
order.
Merge branch 'master' of github.com:dbeniamine/todo.txt-vim

This merge is a commit refactor due to an error in the first commit messages