C/C++: Deal with default parameters in function declarations

* semantic/bovine/c.by (variablearg): Add 'opt-assign'.
C/C++: Parse 'using' statements in the correct order.

(c++-mode:semantic-ctxt-scoped-types): In the case for using
statements outside of function scope, append them in the correct order
instead of using 'cons'.  This is important since using statements may
depend on previous ones.

* tests/cedet/semantic/tests/testusing.cpp: Add test for the above.
Merge branch 'master' into devel