Restructure save games into a zipped bundle.

This is the first step toward bundling all assets related to a save game
into a single item. That makes it easier to avoid clobbering "temporary"
assets from other games like the state.json, but also makes it easier
for players to file bug reports, since there's only a single asset to
upload.

This is only the first step because so far it only includes the various
save files: start of turn, end of last turn before results processing,
and "latest" (the game saved explicitly by the player).

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -53,9 +53,9 @@ body:
       description: >
         Attach any files needed to reproduce the bug here. **A save game is
         required.** We typically cannot help without a save game (the
-        `.liberation` file found in `%USERPROFILE%/Saved
-        Games/DCS/Liberation/Saves`), so most bugs filed without saved games
-        will be closed without investigation.
+        `.liberation` (or `.liberation.zip`, for 7.x) file found in
+        `%USERPROFILE%/Saved Games/DCS/Liberation/Saves`), so most bugs filed
+        without saved games will be closed without investigation.
 
 
         Other useful files to include are:
@@ -74,7 +74,9 @@ body:
         The `state.json` file for the most recently completed turn, located at
         `<Liberation install directory>/state.json`. This file is essential for
         investigating any issues with end-of-turn results processing. **If you
-        include this file, also include `last_turn.liberation`.**
+        include this file, also include `last_turn.liberation`** (unless the
+        save is from 7.x or newer, which includes that information in the save
+        automatically).
 
 
         You can attach files to the bug by dragging and dropping the file into