src/ takes precedence over contrib/

src/lua/Lua.h and contrib/lua/lua.h were conflicting on case-insensitive
filesystems like Windows and OSX (with non-portable include path support)
Ideally we want contrib/lua to have a different name, as we include lua
via #include <lua.hpp> and not #include <lua/lua.hpp>

CMakeLists.txt

@@ -34,7 +34,7 @@ if (MSVC)
 
 	# Use M_PI/M_E macros from math.h
 	add_definitions(-D_USE_MATH_DEFINES -DHAVE_M_PI)
-	
+
 	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /MP")
 	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /MP")
 endif (MSVC)
@@ -217,8 +217,8 @@ find_package(OpenGL REQUIRED)
 add_subdirectory(contrib/lz4)
 
 include_directories(
-	${CMAKE_SOURCE_DIR}/contrib
 	${CMAKE_SOURCE_DIR}/src
+	${CMAKE_SOURCE_DIR}/contrib
 	${ASSIMP_INCLUDE_DIRS}
 	${FREETYPE_INCLUDE_DIRS}
 	${OPENGL_INCLUDE_DIRS}
@@ -328,7 +328,7 @@ if(MSVC)
 	add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
 		COMMAND xcopy ..\\pioneer-thirdparty\\win32\\bin\\x64\\vs2017\\*.dll $(TargetDir)*.dll /Y /C
 		WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
-		COMMENT "copy the dlls into the directory" 
+		COMMENT "copy the dlls into the directory"
 		VERBATIM
 	)
 endif(MSVC)