GetAttributeNode updated to handle special cases of names and dimnames and
reused in both attr builtin and Rf_getAttrib RFF function.

There is fast-path implementation that handles single thread case until
another thread appears in which case we transfer to interpreter, invalidate,
and fallback to more generic implementation.

remove unnecessary implicit Raw/Complex casts from RTypes and ensure wrapping of scalar vectors in FFIWrapNode

fix file.copy, allow LC_ALL in Sys.setlocale, various functions from utils.c, implement CDDR, CADR, ...