Version 1.0.0

Version 1.0.0 comes with a lot of breaking changes and some improvements.
The main change is to the formatting and handling of .formatter.exs. For this
the module Rewrite.DotFormatter has been added. This module provides an API to
the Elixir formatting functionality and the formatter configuration via
.formatter.exs.

Other changes concern the argument list of some functions, here some arguments
have been removed from the argument list and moved to the options.

• Rewrite.TextDiff has been moved to its own package
  (hex: text_diff).

• Add Rewrite.DotFormatter to handle the formatting of sources and files.

• The functions Rewrite.Source.Ex.format/2,
  Rewrite.Source.Ex.put_formatter_opts/2 and
  Rewrite.Source.Ex.merge_formatter_opts/2 are removed.
  The formatting functionality has been moved to Rewrite.DotFormatter.

• Add Rewrite.create_source/4 to create a Source struct without adding it
  to the Rewrite project.

• Add Rewrite.new_source/4 to cretae a Source struct and add it to the
  Rewrite project.

• The Rewrite.Source.update/4 function accepts now an updater function or a
  value.

• Add Rewrite.dot_formatter/1/2 to set and get formatters.

• Add Rewrite.format/2 and Rewrite.fromat!/2 to format a project.

• Add Rewrite.format_source/3 to format a source in a project.

• Add Rewrite.Hook, a behaviour to set as :hooks in a %Rewrite{} project.

• Add Rewrite.Source.default_path/0 and callback
  Rewrite.Filetype.default_path/0.

• Rewrite.new/1, Rewrite.new!/2 and Rewrite.read!/3 now expect an optional
  options list instead of a list of Rewrite.Filetypes.

• The function Rewrite.Source.form_string/3 and the callback
  Rewrite.Filetype.from_string/3 are changed to from_string/2. The argument
  path is now part of the options.