Allow empty lines in multi-line blocks

[stefan-pdx]

Hi,

I noticed that having empty lines in a multi-line block renders a Text bock not terminated with ||| exception.

Example:

{
  message: |||
    Hello

    World
  |||
}

(note the blank line has no spaces)

results in:

STATIC ERROR: test.jsonnet:2:12: Text block not terminated with |||

YAML on the other hand allows you to have empty lines without spaces for indentation. Example:

message: |
  Hello

  World

[sparkprime]

Good point, and probably a one-line fix :)