The grammar now permits blank lines in recipes.
Note that inside of recipes, the token `NEWLINE` is used instead of the
non-terminal `eol`. This is because an `eol` optionally includes a
comment, whereas inside recipes bodies comments get no special
treatment.
If a `#...` comment appears on the line immediately before a recipe, it
is considered to be a doc comment for that recipe.
Doc comments will be printed when recipes are `--list`ed or `--dump`ed.
Also adds some color to the `--list`ing.
Fixes#84
Looks like this:
```make
recipe argument default-argument='default value':
echo argument is {{argument}}
echo default-argument is {{default-argument}}
```
Thanks @deckarep for the feature request!
Fixes#49
