Fix shebang and header ordering

[rhendric]

Earlier support for shebang lines in the compiled output moved them before the default function wrapper, but not before the default LiveScript header comment. This moves shebangs above the header comment as well.

Fixes #1030.

---

#1030 seems like a reasonable request to me, but I might be missing some reason not to do this—speak up here if you can think of any. (There's some prior discussion at #497, which mostly just rejects new explicit compiler options in favor of the existing workarounds, but nobody proposed what #1030 proposes.) I'll hold this PR for two weeks, merging on or after April 10 if there are no objections.

Edit: It looks like #1030 as written isn't a good idea, so this PR now targets this comment.

[rhendric]

(One possible reason to object: shebangs ought to refer to a file's actual contents, not the contents of a derived file. #!/usr/bin/env node is technically incorrect for LS files. Conversely, an LS script can correctly use #!/usr/bin/env lsc and be executable, but with this change if that file were also to be compiled, the output would have an incorrect shebang.)

[pepkin88]

For files intended to run with lsc, shebang should be:

#!/usr/bin/env lsc

But for files intended to be compiled with lsc and then run with node, the shebang line should be:

``#!/usr/bin/env node``

just like in example from #1030.
Why? Because it doesn't introduce any new syntax or exception to a rule.
Moreover, there wouldn't be incorrect shebangs left in files. The first example would strip the comment with an lsc shebang from the compiled file (correct), in the second example ``#! shouldn't be interpreted as a shebang (correct).

Flipping lines can stay, but I would rather test the compiled code for starting from #!.

[rhendric]

@nazar-pc, what do you think about that? If

``#!/usr/bin/env node``
console.log 'Hello'

compiled by default to

#!/usr/bin/env node
// Generated by LiveScript 1.5.0
(function(){
  console.log('Hello');
}).call(this);

would that look good to you?

[nazar-pc]

Having both support for running original script with LiveScript and compiled with Node directly seems highly unlikely, but still possible.

So if I understand correctly

#!/usr/bin/env lsc
``#!/usr/bin/env node``
console.log 'Hello'

would be still compiled by default to

#!/usr/bin/env node
// Generated by LiveScript 1.5.0
(function(){
  console.log('Hello');
}).call(this);

and work properly all the time.

I'm fine with that, makes perfect sense.

[nazar-pc]

Found minor issue with this:

/**
 * Whatever
 */

is compiled to

/**
 * Whatever
 */
// Generated by LiveScript 1.5.0

instead of previous

// Generated by LiveScript 1.5.0
/**
 * Whatever
 */

GitHub seems to use this header for identifying whether *.js file is standalone or was compiled from other language like LiveScript and starts showing incorrect distribution of languages used by project.

Would you be so kind to fix this and add one more test case?

[rhendric]

I'll look into it, thanks!