Add COMPOSITE_* versions of several mainline terrain graphics macros

Macros included:

GENERIC_SINGLE_PLFB, OVERLAY_PLFB, OVERLAY_PL, OVERLAY_L,
BORDER_RESTRICTED_PLFB, TRANSITION_RESTRICTED_PLFB,
TRANSITION_RESTRICTED_LF.

These are extended to take a last argument specifying an image path
function to apply on the tile images.
Add Fake Fog (^Zow) terrain overlay
Add Event Flag terrain overlays A through F
E1S9.2: Add fake fog and fading effect for the event were Elyssa appears

The fading effect is implemented using event flag overlays. The sequence
timing still needs some adjustments.

The terrain mask used in the event has been updated with fake fog
terrain overlays and some earthy rockbound cave terrain hexes.