move project/cmake to top; set OpenGL_GL_PREFERENCE to LEGACY since we use GL2 and GLNVD is for GL3 and up (https://github.com/openscenegraph/OpenSceneGraph/issues/639); set our RTD to point to stable and not master, stable follows our latest stable release

CMakeLists.txt

@@ -1,3 +1,6 @@
+project(OpenMW)
+cmake_minimum_required(VERSION 3.1.0)
+
 # Apps and tools
 option(BUILD_OPENMW             "Build OpenMW" ON)
 option(BUILD_LAUNCHER           "Build Launcher" ON)
@@ -13,17 +16,14 @@ option(BUILD_WITH_CODE_COVERAGE "Enable code coverage with gconv" OFF)
 option(BUILD_UNITTESTS          "Enable Unittests with Google C++ Unittest" OFF)
 option(BULLET_USE_DOUBLES       "Use double precision for Bullet" OFF)
 
+set(OpenGL_GL_PREFERENCE LEGACY)  # Use LEGACY as we use GL2; GLNVD is for GL3 and up.
+
 if (NOT BUILD_LAUNCHER AND NOT BUILD_OPENCS AND NOT BUILD_WIZARD)
    set(USE_QT FALSE)
 else()
    set(USE_QT TRUE)
 endif()
 
-# set the minimum required version across the board
-cmake_minimum_required(VERSION 3.1.0)
-
-project(OpenMW)
-
 # If the user doesn't supply a CMAKE_BUILD_TYPE via command line, choose one for them.
 IF(NOT CMAKE_BUILD_TYPE)
     SET(CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING
@@ -58,7 +58,7 @@ set(OPENMW_VERSION_COMMITDATE "")
 
 set(OPENMW_VERSION "${OPENMW_VERSION_MAJOR}.${OPENMW_VERSION_MINOR}.${OPENMW_VERSION_RELEASE}")
 
-set(OPENMW_DOC_BASEURL "https://openmw.readthedocs.io/en/master/")
+set(OPENMW_DOC_BASEURL "https://openmw.readthedocs.io/en/stable/")
 
 set(GIT_CHECKOUT FALSE)
 if(EXISTS ${PROJECT_SOURCE_DIR}/.git)