Fix linker errors.

Applications/DataExplorer/Base/CMakeLists.txt

@@ -37,7 +37,7 @@ add_library(QtBase
 )
 
 target_link_libraries(QtBase
-    Qt5::Gui
+    Qt5::Widgets
     GeoLib)
 
 set_property(TARGET QtBase PROPERTY FOLDER "DataExplorer")

Applications/Utils/OGSFileConverter/CMakeLists.txt

@@ -13,7 +13,7 @@ set(SOURCES
     OGSFileConverter.cpp
 )
 
-find_package(Qt4 QUIET REQUIRED)
+find_package(Qt5 QUIET REQUIRED Gui Widgets Xml XmlPatterns)
 
 include_directories(
     ${CMAKE_BINARY_DIR}/Applications/Utils/OGSFileConverter
@@ -47,8 +47,6 @@ target_link_libraries(OGSFileConverter
     GeoLib)
 ADD_VTK_DEPENDENCY(OGSFileConverter)
 
-include(${QT_USE_FILE})
-
 set(CMAKE_CONFIGURATION_TYPES "Release;Debug" CACHE TYPE INTERNAL FORCE)
 set(EXECUTABLE_OUTPUT_PATH ${CMAKE_BINARY_DIR}/bin)
 set(LIBRARY_OUTPUT_PATH ${CMAKE_BINARY_DIR}/lib)

scripts/cmake/Find.cmake

@@ -96,6 +96,9 @@ find_package(Metis QUIET)
 
 ## Qt5 library ##
 if(OGS_BUILD_GUI)
+    if(USE_CONAN)
+      set(Qt5_DIR ${CONAN_QT_ROOT}/lib/cmake/Qt5)
+    endif()
     find_package( Qt5 5.5 REQUIRED Gui Widgets Xml XmlPatterns)
     cmake_policy(SET CMP0020 NEW)
     if(CMAKE_CROSSCOMPILING)