[m-dev.] Change grade handling

[Fergus Henderson]

A few small suggestions:

> +	--->	gcc_ext		% gcc extensions see grade_component_table

s/extensions see/extensions -- see/

> +	;	par		% parallelism / MT

s/MT/multithreading/

> +	;	pic		% Do we need to reserve a register for PIC?

s/PIC/PIC (position independent code)/

doc/user_guide.texi:
> +The @var{grade} should be a @samp{.} separated list of the
> +grade options to set. The grade options may be given in any order.
> +The available options each belong to a set of mutually
> +exclusive alternatives governing a single aspect of the compilation model.
> +The set of aspects and their alternatives are:
> + at table @asis
> + at item What combination of GNU-C extensions to use:
> + at samp{none}, @samp{reg}, @samp{jump}, @samp{asm_jump},
> + at samp{fast}, and @samp{asm_fast} (the default is system dependent).
> +
> + at item What garbage collection strategy to use:
> + at samp{.gc}, and @samp{.agc} (the default is no garbage collection).

Since they're suppsed to be `.'-separated, shouldn't you omit the `.'
at the start of the names here?

> + at item What kind of profiling to use:
> + at samp{.prof}, @samp{.proftime}, @samp{.profcalls}, and @samp{.memprof}
> +(the default is no profiling).

`.proftime' and `.profcalls' should be commented out here
(this is a bug in the existing documentation that I happened
to notice while reviewing your changes).

> + at item What debuging features to enable:
> + at samp{.debug} (the default is no debuging features).

s/debuging/debugging/

Otherwise that looks fine.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
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