E3S8B: Use initial in-scenario music for the storyscreen
E3S8B: Recall Durvan's loyals offscreen during prestart

The RECALL_SIDE_LOYALS commands cause the viewport to scroll to Durvan
during the initial sequence, which is somewhat annoying considering the
focus of that scene is supposed to be Anya's party, not Durvan's.
Therefore it's better to just recall Durvan's units before the display
is initialized.
Fix Aragwaith Captain using the Aragwaith Ancient Banner's baseframe on attack
E3S8B: Fix the Hemera boss event removing too much shroud around the chamber
E3S8B: Use surface hive terrain and unit variations for Hemera's chamber
Strip optional whitespace from all map and terrain mask files

This extra whitespace is generated by all map editor versions before
1.11.x, but since 1.11.x maps are forcefully saved without it, which
results in unnecessarily large diffs every time an existing map file is
modified with the 1.11.x editor. Thus I might as well get this out of
the way now.