(svn r7299) -CodeChange: Train and Aircraft Build window GUI code simplified a bit:

- using one engine list instead of 3
- removed engine filters (loco, wagons, helicopters, etc.)
- EngineList code isolated from GUI (moved to helpers.cpp - reusing CBlobT code which does exactly what is needed for EngineList)
- removed unnecessary  "optimization" (rebuild and sort engine list on each WE_PAINT)

Makefile

@@ -707,6 +707,7 @@ SRCS += gfx.c
 SRCS += gfxinit.c
 SRCS += graph_gui.c
 SRCS += heightmap.c
+SRCS += helpers.cpp
 SRCS += industry_cmd.c
 SRCS += industry_gui.c
 SRCS += intro_gui.c