This introduces five new metadata nodes:
* `do` - contains metadata about do location in a function call with
`do/end` blocks
* `end` - contains metadata about end location in a function call with
`do/end` blocks
* `closing` - contains metadata about the closing pair, such as a `}`
in a tuple or in a map, or such as the closing `)` in a function call
with parens
* `eol` - is set to true when the opening pair, such as `{` or `(`, are
followed by the end of the line
* `delimiter` - contains the opening for sigils (such as `"{"`, `"/"`,
etc)
José Valim
faefb0b882