Set C++17 as default

meson.build

@@ -3,7 +3,7 @@ project(
   version : '0.1',
   default_options : [
     'warning_level=1',
-    'cpp_std=c++2a'
+    'cpp_std=c++17'
   ]
 )
 

src/csg/meson.build

@@ -11,6 +11,4 @@ lib_csg_parser = static_library('csg-parser',
   dependencies: [pegtl, cgal],
   install : true)
 
-if get_option('cpp_std')=='c++2a'
-  subdir('tests')
-endif
+subdir('tests')