Spelling fixes

[Waldek Hebisch]

Qian, it is very good that you fix spelling. However, maybe
you could be a bit more conservative. In one case I see
'specialised' changed to 'specialized'. AFAIK 'specialised'
is preferred British spelling. In another case I see:

++ interval(x,y) creates a new interval \spad{[x,y]}, if
- ++ \spad{x<=y} and $\spad{[y,x]}, if \spad{y<x}.
+ ++ \spad{x<=y}; returns \spad{[y,x]}, if \spad{y<x}.
qinterval : (R, R) -> %

I do not know what linguist would say, but the original for me
looks like things that appear in math texts and should be very
clear to any mathematician. Replacement is confusing, it is
written as if in one case function did not return anything
and only the second case returend something. So regardless
of language correctness, from information point of view the
second version looks worse.

--
Waldek Hebisch

[Qian Yun]

Thanks, please revert anything you feel necessary.
I'll be more careful in the future, post potential controversial
changes for review first.

On the subject, I have some fixes in staging, questions:

1. Rename C function "writeablep" to "writablep".

2. Closure CL -> Clozure CL

- Qian