Migrate to Twine 2 format

The goal of this MR is to migrate output to Twine 2 format, that handles JS files in a different way. Instead of putting them in <div> tags, single div per file, in the twine 2 mode tweego joins all the .js files and put the result in a global <script> tag.

Please let me know your opinions on the changes to the sugarcube files.

Tweego outputs in twine2 mode when story format file is named format.js, so please find below is a brief guide on producing the patched version of the SuragCube's format.js file:

Preparations:

1. Install node.js (https://nodejs.org/en/download/)
2. Install Mercurial (https://www.mercurial-scm.org/)
3. Clone Sugarube repo: hg clone https://bitbucket.org/tmedwards/sugarcube
4. cd into the directory of the suragcube clone (i.e. cd sugarcube if you ran hg from a terminal).
5. Set active branch to "v2-release": hg checkout v2-release
6. Run npm install in the repo dir. On Windows it will probably be node npm install. Requited dependences change during the project lifetime and vary from branch to branch; you may need to run npm install again after some time, or after branch/tag change. Try to run it in case of strange build errors.

The next is done in the directory where SC repo was cloned. Loop over required SugarCube versions:

1. hg update --clean to clean any local changes
2. hg checkout v2.28.2 (any tag or head here, of course)
3. hg patch --no-commit ~/games/fc-pregmod/devNotes/sugarcube\ stuff/sugarcube-fc-changes.patch
4. node build.js -b 2 to build release version
5. cp dist/twine2/sugarcube-2/format.js <whenever you want>
6. node build.js -b 2 -u -d to build debug version
7. cp dist/twine2/sugarcube-2/format.js <whenever you want to place the debug header>

At version 2.24.0 the patch did not apply completely, because in 2.25.0 they added some comments. I applied the rejected part manually and made a new patch file to use it with versions 2.24 and older: hg diff src/ > <file to place patch in>.