perf(const): const changed to a singelton

const needds to be accessed all throughout so it has been changed to a singleton to allow for more efficient usage

BREAKING CHANGE: Any previous loads to const will break, also constant->Constant and constants->Constants

src/const/meson.build

@@ -12,6 +12,7 @@ libconst = library('const',
     const_sources, 
     include_directories: include_directories('public'),
     cpp_args: ['-fvisibility=default'],
+    dependencies: [const_dep],
     install : true)
 
 # Make headers accessible