Deprecate function-call syntax for thunks #374
Description
Thunks really seem to have become monads, with upcoming linear algebra support and so on. Semantically, they seem closer to a Ref than a Function. So I propose to deprecate the mythunk() syntax. It should be mythunk[] instead, if we need a short syntax - but then, that might lead to error prone or confusing code if the thunk might contains an array, etc. Since users typically won't have to "dereference" a thunk, I would propose to leave unthunk as the sole way to get the "contents" of a thunk.
Related to #373.