Moving manuel tasks to dotfiles.sh

dotfiles.sh is a standalone version of the manuel task runner, combined
with the existing dotfile tasks previous contained in the manuelfile.
Linking functions for dotfiles, based on existing Rake tasks

There are some minor differences between the bash tasks and the rake
tasks, including:

- existing files in `link` are displayed immediately rather than
  gathered together and displayed at the end
- existing files aren't checked against source files for similarity
  before backing up.

In both cases, the operations were not necessary and are being
deferred.
Removing unused utility functions from dotfiles.sh
Refactoring dotfiles.sh to have iteration handled in separate function
Expanding help for dotfiles tasks
Correcting typo in `dotfiles status` help text
Fixing typo in dotfiles.sh help text
Renaming _each_file function to _each_dotfile in dotfiles script
Condensing dotfile help text
Add dotfiles backup-status command.
Refactoring and commenting dotfiles.sh _each_dotfile function

Assigning first arugment to a $per_file_command variable to make it
clearer what this argument is. Adding comment to clarify variable access
in sub-functions.
Updating example task group in dotfiles.sh

This section wasn't previously updated for the changes in f4d7901eb
Updating task group example in dotfiles.sh
Reorganizing dotfiles.sh
Better help text in `dotfiles help`

Adding `--pretty` option to `dotfiles tasks` to display formatted task
list.
Using heredoc for dotfiles help
Adding help information for additional dotfiles tasks.
Using heredocs for linking-related dotfiles tasks
Removing additional blank lines in dotfiles
Ascii dotfiles for dotfiles.sh