EMI: Fix movies for boulder puzzle on vista point

- enhance search for BINK header (some movie files don't have a
  SMUSH header)
delete stream object when returning false
EMI: fix pause handling

On vista point it may happen that two sequences for the rock landings
are executed at the same time. Although they intend to be locked via
pause_scripts(), changing the set will call unpause_scripts() and unlock
all of them.

The patch will use the optional parameter for (un)pause_scripts() to
determine whether the pause calls should be counting (e.g. when
switching a set or opening the inventory) or not.
Merge remote-tracking branch 'chkr/movie-fixes' into hacking
Merge remote-tracking branch 'chkr/pause-handling' into hacking
GRIM/EMI: Ignore Actor:walkTo() if destination is unreachable

The path to the Curch of LeChuck has bogus coordinates as out point, so
the game will walk Guybrush to an invalid position when entering that
set. This patch will detect when no path can be found to the destination
position and ignore the walkTo() request in that case.
EMI: Separate radius and center for mesh collision sphere