Some minor adaptions to prepare for typing of quantified expressions

1. Fixed wrong signature adaption of identifiers and global features.

2. Accu and Accus have the context as an attribute.

3. Removal of some attributes in 'Accus' and of the function 'pop'.
The application always calls with

    expect_function nargs ...
    expect_argument i ...
    complete_function nargs ...

Therefore no stack is necessary and no tracking the the already processed
number of arguments.

	modified:   context.ml
	modified:   context.mli
	modified:   signature.ml
	modified:   typer.ml
	modified:   class_table.ml
Manifest predicates implemented

	modified:   parser.mly
	modified:   support.ml
	modified:   typer.ml