Ruby 1.9 fixes.

SF Bug#1292 - Runtime fixes for Proc changes in ruby-1.9 when using STL wrappers that override the default predicate, such as:

  %template(Map) std::map<swig::LANGUAGE_OBJ, swig::LANGUAGE_OBJ, swig::BinaryPredicate<> >;

Fixes li_std_functors testcases for Ruby 1.9.

Also rb_respond_to return values have changed subtely in 1.9 and return should be treated as a flag instead of checking for Qtrue, see SF Bug #1159.

Also fix li_std_map, li_std_set silently failing - rb_protect behaviour seems to have changed when an exception is thrown, so code has been changed to use rb_rescue. A call to 'rb_set_errinfo(Qnil)' could have solved this after the rb_protect call, but it is only available in 1.9+ and Ruby API changes are not easily and transparently detectable.
More rb_protect rewrite to use rb_rescue for Ruby 1.9
Rewrite Ruby's GC_VALUE without use of macros for easier debugging