Add warning for plugins without masters

[Freso]

Plugins without any MASTers set will get removed from the load order by the engine (at least Fallout4.exe, haven't tested with others). As such it might be nice for LOOT to show a warn or error either at the top or by individual plugins that do not have a MAST (at the very least if they're also active, but possibly even if not).

This should probably be tested for other engines as well.

Dummy Plugin.zip is an empty plugin for Fallout 4 without any MAST.

[Ortham]

At least for Oblivion it was valid for plugins to have no masters, which was useful for mods to be compatible with Oblivion and the Nehrim total conversion.

[Freso]

Well, the Creation Kit also didn't give me any errors when I created my empty dummy plugins, but I saw someone mention it in one of the Discord servers I'm in and decided to test it—and indeed, if I have any active non-MAST plugins and I open the game and start a new save and exit out, the plugins will now have been deactivated.

[Ortham]

We'll have to test which games have which behaviour: I suspect it'll correlate with whether the game has hardcoded plugins.

[Ortham]

I can't replicate this, I:

1. Added a line *Dummy Plugin.esp to plugins.txt then saved it
2. Launched Fallout 4
3. Loaded a saved game
4. Quit to desktop
5. Opened plugins.txt.

*Dummy Plugin.esp is still present. This was also the case with Skyrim SE.

[HylianSteel]

You can replicate this if you change step 4 to quitting to main menu.
Step 5 to clicking on Mods, then going back to main menu, then quitting to desktop.
and then finally step 6 would be Opened plugins.txt.
These are tested steps on Skyrim SE and they should also work on Fallout 4.

[Ortham]

These are tested steps on Skyrim SE and they should also work on Fallout 4.

I just tried those steps with Skyrim SE and a plugin with no MAST subrecords and some BPTD records, and still couldn't replicate...

[IllusiveMan196]

Results takes directly from my load orders (some with plugin examples, some without), all are managed by Wrye Bash / Mash:
Morrowind - many mods that add new content are masterless. Some may even edit existing content (need proof).
Oblivion - best example is Dynamic Map.esp, masterless non-empty plugin.
Skyrim - many asset packs (textures, meshes, fixed assets, scripts, lod) are loaded by game and lodgen/dyndolod.
Fallout 3 - CASM (Cipscis' Automatic Save Manager) is masterless, non-empty plugin.
Fallout New Vegas - Vanilla UI Plus.esp is masterless, despite having quest and script records.
Fallout 4 - same as Skyrim, asset packs and fixes.

No masterless plugins in my load orders are disabled or ignored by game as far as I can tell.
What I can see as a possible reason to add this functionality is if by some chance plugin manages to edit vanilla record (although this should be hard to accomplish (might test it some time later)) and doesn't have vanilla game masters listed. Or it is for another game entirely. Given that LOOT now scans bsa too, it'd be nice to scan for bsa/ba2 match betwen game versions.