Todo.txt support with existing *.txt filetype setup

[drasch]

My VIM has an existing mapping for BufRead,BufNewFile. I had to make the included change to enable todo.txt to use the task filetype. I did this by manually setting the filetype with "set ft=" instead of "setfiletype" based on the help article below where "setfiletype" chceks for !did_filetype.

From the Vim Help,
:setf[iletype] {filetype} :setf :setfiletype
Set the 'filetype' option to {filetype}, but only if
not done yet in a sequence of (nested) autocommands.
This is short for: >
:if !did_filetype()
: setlocal filetype={filetype}
:endif

output from :autocmd * *.txt,todo.txt

--- Auto-Commands ---
filetypedetect BufNewFile
*.txt setf text
todo.txt set ft=task
filetypedetect BufRead
*.txt setf text
todo.txt set ft=task