Change behavior of generating translations

- translations are now generated by default with Python as required
   dependency
 - old behavior of installing only English files is provided as an
   option (configure with -DTRANSLATIONS=0)

CMakeLists.txt

@@ -1,9 +1,11 @@
 cmake_minimum_required(VERSION 2.8)
 
-find_package(PythonInterp 2.7)
+option(TRANSLATIONS "Enable translations of help and level files" ON)
 
-if(NOT PYTHONINTERP_FOUND)
-    message(WARNING "Python not found, help and level files will NOT be translated!")
+if(TRANSLATIONS)
+    find_package(PythonInterp 2.7 REQUIRED)
+else()
+    message(STATUS "Translations disabled; only English files will be installed")
 endif()
 
 if(NOT DEFINED COLOBOT_INSTALL_DATA_DIR)

help/CMakeLists.txt

@@ -9,12 +9,14 @@ set(HELP_INSTALL_DATA_DIR  ${COLOBOT_INSTALL_DATA_DIR}/help)
 ##
 function(add_help_category help_category_dir install_subdir)
 
-    message(STATUS "Adding translation targets for help/${help_category_dir}")
-
+    # Always install English files
     file(GLOB english_help_files ${help_category_dir}/E/*)
     install(FILES ${english_help_files} DESTINATION ${HELP_INSTALL_DATA_DIR}/E/${install_subdir})
 
-    if(PYTHONINTERP_FOUND)
+    # If translations are turned on, also generate translated files
+    if(TRANSLATIONS)
+        message(STATUS "Adding translation targets for help/${help_category_dir}")
+
         set(work_dir ${DATA_BINARY_DIR}/help-po/${help_category_dir})
         generate_translations(translated_help_files
                               "help"

levels/CMakeLists.txt

@@ -9,14 +9,14 @@ set(LEVEL_INSTALL_DATA_DIR ${COLOBOT_INSTALL_DATA_DIR}/levels)
 ##
 function(add_level_category level_category_dir)
 
-    message(STATUS "Adding translation targets for level/${level_category_dir}")
-
-    # Without Python, just install all files as they are
-    if(NOT PYTHONINTERP_FOUND)
+    # If translations are turned off, just install all files as they are
+    if(NOT TRANSLATIONS)
         install(DIRECTORY ${level_category_dir} DESTINATION ${LEVEL_INSTALL_DATA_DIR})
         return()
     endif()
 
+    message(STATUS "Adding translation targets for level/${level_category_dir}")
+
     add_chaptertitles(${level_category_dir})
 
     file(GLOB level_dirs RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} ${level_category_dir}/chapter*/level*)