Formatting: normalise back to 4-space indentation.

In several pieces of development recently I've run across the
occasional code block in the middle of a function which suddenly
switched to 2-space indent from this code base's usual 4. I decided I
was tired of it, so I ran the whole code base through a re-indenter,
which made a huge mess, and then manually sifted out the changes that
actually made sense from that pass.

Indeed, this caught quite a few large sections with 2-space indent
level, a couple with 8, and a handful of even weirder things like 3
spaces or 12. This commit fixes them all.

terminal/terminal.c

@@ -1073,7 +1073,7 @@ static int sblines(Terminal *term)
     int sblines = count234(term->scrollback);
     if (term->erase_to_scrollback &&
         term->alt_which && term->alt_screen) {
-            sblines += term->alt_sblines;
+        sblines += term->alt_sblines;
     }
     return sblines;
 }