- Apply mechanism to decide use for IrrXML external or internal

Several distributions usually decide for shared external libraries
instead of an usual embedded, for security reasons, duplicatiion issues.
This change enable the possibility to set SYSTEM_IRRXML=ON for detect
and build against a system installed irrxml.
By default, the internal copy is compiled.

Changes on build:
- Added a FindIrrXML cmake module.
- Moved the source recipe for proper CMakeLists inside contrib directory
- Includes aren't path based anymore, using the provided INCLUDE_DIR
- Compiler option are grouped in a singled entry on main CMakeLists

Note: Current internal assimp irrXML is older than upstream irrlicht 1.8.4.
To enable usage of this version, code need to be patched.

code/CMakeLists.txt

@@ -569,6 +569,9 @@ SET( PostProcessing_SRCS
 )
 SOURCE_GROUP( PostProcessing FILES ${PostProcessing_SRCS})
 
+SET( IrrXML_SRCS irrXMLWrapper.h )
+SOURCE_GROUP( IrrXML FILES ${IrrXML_SRCS})
+
 ADD_ASSIMP_IMPORTER( Q3D
   Q3DLoader.cpp
   Q3DLoader.h
@@ -681,18 +684,6 @@ SET( Extra_SRCS
 )
 SOURCE_GROUP( Extra FILES ${Extra_SRCS})
 
-SET( IrrXML_SRCS
-  irrXMLWrapper.h
-  ../contrib/irrXML/CXMLReaderImpl.h
-  ../contrib/irrXML/heapsort.h
-  ../contrib/irrXML/irrArray.h
-  ../contrib/irrXML/irrString.h
-  ../contrib/irrXML/irrTypes.h
-  ../contrib/irrXML/irrXML.cpp
-  ../contrib/irrXML/irrXML.h
-)
-SOURCE_GROUP( IrrXML FILES ${IrrXML_SRCS})
-
 SET( ConvertUTF_SRCS
   ../contrib/ConvertUTF/ConvertUTF.h
   ../contrib/ConvertUTF/ConvertUTF.c
@@ -848,7 +839,8 @@ SET( assimp_src
 ADD_DEFINITIONS( -DOPENDDLPARSER_BUILD )
 
 INCLUDE_DIRECTORIES(
-  ../contrib/openddlparser/include
+    ${IRRXML_INCLUDE_DIR}
+    ../contrib/openddlparser/include
 )
 
 IF (ASSIMP_BUILD_NONFREE_C4D_IMPORTER)
@@ -858,7 +850,7 @@ ENDIF (ASSIMP_BUILD_NONFREE_C4D_IMPORTER)
 
 ADD_LIBRARY( assimp ${assimp_src} )
 
-TARGET_LINK_LIBRARIES(assimp ${ZLIB_LIBRARIES} ${OPENDDL_PARSER_LIBRARIES} )
+TARGET_LINK_LIBRARIES(assimp ${ZLIB_LIBRARIES} ${OPENDDL_PARSER_LIBRARIES} ${IRRXML_LIBRARY} )
 
 if(ANDROID AND ASSIMP_ANDROID_JNIIOSYSTEM)
   set(ASSIMP_ANDROID_JNIIOSYSTEM_PATH port/AndroidJNI)

code/irrXMLWrapper.h

@@ -42,7 +42,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define INCLUDED_AI_IRRXML_WRAPPER
 
 // some long includes ....
-#include "./../contrib/irrXML/irrXML.h"
+#include <irrXML.h>
 #include "./../include/assimp/IOStream.hpp"
 #include "BaseImporter.h"
 #include <vector>