Add turning boat faces to face set.

They're just derived from the base set images, and reduced to the XPM palette at this point.

ChangeLog.rtro

@@ -3,6 +3,7 @@ Changes for top of trunk
 ------------------------
 2021-09-04 Daniel Hawkins
 	* road/yellow/yellow_*.rtro.111.png: Reduce to XPM palette.
+	* transport/turningboat.rtro.x*1.png: Add 48x48 faces for turning boat, derived from base set images and reduced to XPM palette.
 
 2021-09-02 Daniel Hawkins
 	* weapon/hammer/hammer_2.rtro.1*.png: Borrow hammer faces from 0.93.4 instead of earlier versions

TODO.rtro

@@ -35,14 +35,6 @@ Images missing faces in the retro tileset:
 ./system/blocked_red.111
 ./system/event_trigger.111
 ./system/event_time.111
-./transport/turningboat.x51
-./transport/turningboat.x11
-./transport/turningboat.x41
-./transport/turningboat.x21
-./transport/turningboat.x81
-./transport/turningboat.x71
-./transport/turningboat.x31
-./transport/turningboat.x61
 ./monster/humanoid/Elf/dark_elf2.131
 ./monster/humanoid/Elf/dark_elf.132
 ./monster/humanoid/Elf/dark_elf2.132