Small optimization (use partition instead of two filters with opposite predicates)
foreach(dir
"Bamboo"
"Bath"
"City"
"EarthRise"
"Freeway"
"hell"
"Island"
"nature"
"Planes"
"Sheep"
"Snow"
"cheese"
"Underwater")
add_subdirectory(${dir})
endforeach(dir)
install(FILES themes.cfg DESTINATION ${SHAREPATH}Data/Themes)