add eval-on-region and eval-on-current-line functions
add string-to-quoted-on-region and string-to-quoted-on-current-line functions
add local key bindings for eval and quoted functions
use a temporary file to eval elixir code, instead string evaluation through elixir command
update inline documentation about new eval functions
add information about customize-group into inline documentation
update README with new function information
add eval-on-current-buffer function
Merge branch 'add-elixir-eval-functions'
add changelogs for release 1.3.0
prepare 1.3.0