Switch to Qt5

- compile with Qt5 for the GUI
- remove Qt4 from the CMake files

README.md

@@ -70,20 +70,25 @@ licenses for more details.
 
 
 ### Requirements
-g2o requires cmake and Eigen3 to build. The other requirements are optional.
   * cmake             http://www.cmake.org/
   * Eigen3            http://eigen.tuxfamily.org
+
+  On Ubuntu / Debian these dependencies are resolved by installing the
+  following packages.
+    - cmake
+    - libeigen3-dev
+
+#### Optional requirements
   * suitesparse       http://www.cise.ufl.edu/research/sparse/SuiteSparse/
   * Qt5               http://qt-project.org
   * libQGLViewer      http://www.libqglviewer.com/
 
   On Ubuntu / Debian these dependencies are resolved by installing the
   following packages.
-    - cmake
-    - libeigen3-dev
     - libsuitesparse-dev
-    - Qt4: `libqt4-dev`, `qt4-qmake`, `libqglviewer-dev` (Or `libqglviewer-qt4-dev` in modern distributions)
-    - Qt5: `libqt5-dev`, `qt5-qmake`, `libqglviewer-dev`
+    - libqt5-dev
+    - qt5-qmake
+    - libqglviewer-dev
 
 #### Mac OS X
 If using [Homebrew](http://brew.sh/), then

cmake_modules/FindQGLViewer.cmake

@@ -1,13 +1,9 @@
-# Need to find both Qt{4,5} and QGLViewer if the QQL support is to be built
-FIND_PACKAGE(Qt4 COMPONENTS QtCore QtXml QtOpenGL QtGui)
-IF(NOT Qt4_FOUND)
-	FIND_PACKAGE(Qt5 QUIET COMPONENTS Core Xml OpenGL Gui Widgets)
-	IF(NOT Qt4_FOUND AND NOT Qt5_FOUND)
-		MESSAGE("Qt{4,5} not found. Install it and set Qt{4,5}_DIR accordingly")
-		IF (WIN32)
-			MESSAGE("  In Windows, Qt5_DIR should be something like C:/Qt/5.4/msvc2013_64_opengl/lib/cmake/Qt5")
-		ENDIF()
-	ENDIF()
+FIND_PACKAGE(Qt5 COMPONENTS Core Xml OpenGL Gui Widgets)
+IF(NOT Qt5_FOUND)
+  MESSAGE("Qt5 not found. Install it and set Qt5_DIR accordingly")
+  IF (WIN32)
+    MESSAGE("  In Windows, Qt5_DIR should be something like C:/Qt/5.4/msvc2013_64_opengl/lib/cmake/Qt5")
+  ENDIF()
 ENDIF()
 
 FIND_PATH(QGLVIEWER_INCLUDE_DIR qglviewer.h
@@ -19,7 +15,7 @@ FIND_PATH(QGLVIEWER_INCLUDE_DIR qglviewer.h
   )
 
 find_library(QGLVIEWER_LIBRARY_RELEASE
-  NAMES qglviewer-qt4 QGLViewer-qt4 qglviewer QGLViewer QGLViewer2
+  NAMES qglviewer QGLViewer
   PATHS /usr/lib
         /usr/local/lib
         /opt/local/lib
@@ -30,15 +26,15 @@ find_library(QGLVIEWER_LIBRARY_RELEASE
   PATH_SUFFIXES QGLViewer QGLViewer/release
 )
 find_library(QGLVIEWER_LIBRARY_DEBUG
-  NAMES dqglviewer dQGLViewer dQGLViewer2 QGLViewerd2
+  NAMES dqglviewer dQGLViewer dQGLViewer QGLViewerd2
   PATHS /usr/lib
         /usr/local/lib
         /opt/local/lib
         /sw/lib
         ENV QGLVIEWERROOT
         ENV LD_LIBRARY_PATH
         ENV LIBRARY_PATH
-  PATH_SUFFIXES QGLViewer QGLViewer/release
+  PATH_SUFFIXES QGLViewer QGLViewer/debug
 )
 
 if(QGLVIEWER_LIBRARY_RELEASE)