Space after dash in ALL_FIELDS explore fields

[joshtemple]

The following LookML is accepted by the Looker validator, but not by lkml, due to the space after the -. This is because lkml does not consider a space to be a valid part of a literal.

explore: explore_name {
  fields: [- ALL_FIELDS*]
}

[joshtemple]

Since this syntax is non-documented and really breaks assumptions about what a literal is in LookML (they shouldn't be able to contain spaces), I don't think it's worth supporting this syntax. It's a trivial change for the user to make to update to the conventional approach which is -ALL_FIELDS*.