Don't parse __autoconcat__ to sconcat in strict mode

[Pieter12345]

Parse __autoconcat__() to the new __statements__() instead of sconcat() in strict mode. __statements__() takes arguments of any type and returns void for typechecking, so compile errors will be generated in cases where __autoconcat__() used to insert sconcat()s, or in other words, where the user has either forgotten to put some . concat, or where the user has made a mistake.
This change does not affect non-strict mode, as automatically inserting concats is a feature there.
Alias syntax should also remain possible in strict mode, but only when the whole alias is nicely concatenated together by the user. Inserting multiple arguments/statements will cause the code block to be interpreted as a statements block and not as an alias redirect.

[Pieter12345]

This change fixes the following issues in strict mode, but does not affect them in non-strict mode:

• Incorrect [Using undefined variable] error on unassigned variable declarations in autoconcat (non-strict mode) #1179
• Unexpected extra time being taken when import used with large array in a procedure. #814
• (unreported) When running a script from cmdline mode, the sconcat of the script is printed to the console.
  Note that the last issue does not collide with the feature of being able to return value from scripts. One only has to explicitly concat their script together to make it return its value to the console.

[PseudoKnight]

Note that #814 already has a workaround implemented for procedures. The main sconcat is executed but not returned in procedures.

[LadyCailin]

The code here looks good, but let's add something about this in the documentation, since this will break traditional use of aliases if strict mode is enabled. Probably need to make some changes in the introductory documentation to ensure that the best practice (using run()) is mentioned (though we can still show examples of the standard alias syntax).

[Pieter12345]

I believe that leaves us with the following things to do/consider/realize:

• This PR only makes changes to strict mode code.
• This PR breaks /cmd = /cmd1 arg, and maintains support for the preferred version: *:/cmd = run('/cmd1') \ run('/cmd2') , and for the explicit concat and full string versions: /cmd = /cmd1.' arg' and /cmd = '/cmd1 arg'.
• This PR maintains support for /cmd = /cmd1 \ run('/cmd2'), where possible arguments have to be quoted as in the first point.
• It should be considered whether we want to allow unquoted /cmd = /cmd2 (VS /cmd = '/cmd2') commands, as this might feel weird because users would only have to quote command arguments, and handle the unquoted command itself as a string.
• The Beginner's Guide should be updated to at least quote+concat the examples, and perhaps even only include the run() version. This is the place where users can get pushed in a certain desired direction, which might be run('/cmd arg'), but which might also be '/cmd arg'. I'd like to leave that choice with @LadyCailin. The documentation update can be pushed separately from this PR if you want to do it, as this PR only removes existing syntax, and doesn't add new syntax.