Added build player option.

CMakeLists.txt

@@ -12,6 +12,7 @@ OPTION(POLYCODE_BUILD_STATIC "Build Polycode static libraries" OFF)
 OPTION(POLYCODE_BUILD_BINDINGS "Build Polycode Lua bindings" ON)
 OPTION(POLYCODE_BUILD_EXAMPLES "Build Polycode examples" ON)
 OPTION(POLYCODE_BUILD_MODULES "Build Polycode modules" ON)
+OPTION(POLYCODE_BUILD_PLAYER "Build Polycode standalone player" ON)
 OPTION(POLYCODE_BUILD_TOOLS "Build Polycode tools" ON)
 
 # Some non-standard CMake modules
@@ -71,6 +72,7 @@ IF(POLYCODE_BUILD_MODULES)
 ENDIF(POLYCODE_BUILD_MODULES)
 
 IF(POLYCODE_BUILD_PLAYER)
+    FIND_PACKAGE(Lua51 REQUIRED)
     ADD_SUBDIRECTORY(Player/Contents)
 ENDIF(POLYCODE_BUILD_PLAYER)