Requirements set back from c++14 to c++11.

pub/CMakeLists.txt

@@ -22,7 +22,7 @@ configure_file(${CMAKE_SOURCE_DIR}/cmake/scripts/CTestCustom.cmake.in
 #option(FRIDA_MAN "Build a user manual" OFF)
 #option(BUILD_DEBIAN "Build a debian package" OFF)
 
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14 -g -O2 -pedantic -Wall -Wno-sign-compare -Wno-unused-result -Wno-parentheses  -Wno-unknown-pragmas -Werror")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -g -O2 -pedantic -Wall -Wno-sign-compare -Wno-unused-result -Wno-parentheses  -Wno-unknown-pragmas -Werror")
 # to use C99 _Complex, add -fext-numeric-literals to CXX_FLAGS
 
 find_package(Boost REQUIRED) # used header-only modules: format algorithm