semantic: Improve grammar-mode

semantic: Improve grammar-mode

* lisp/cedet/semantic/grammar.el (semantic-grammar-create-package):
 Get the setupfcn and mode before switching to other buffers. Don't
 special eval defvar, we generate defconst now. Be more aggressive
 reparsing open buffers of the mode being updated.
 (semantic-grammar-mode-map): Don't bind M-TAB.
 (semantic-grammar-menu): Use `completion-at-point' instead of grammar
 version.
 (semantic-grammar-mode): Remove type relation character.
 (semantic-grammar-complete): Delete.
 (semantic-ctxt-current-class-list): Also support 'token' class.
 (semantic-analyze-possible-completions): Support the optional FLAGS
 that are passed in for other languages. Reverse the found prefix.