[developers] minor LKB code changes

[Ann Copestake]

Summary:

change to interface for `Apply all lex rules'.  info re algebra code

Details:

I have changed the interface function `Apply all lex rules' that can be called
from a display of a lexical entry.  Originally this produced separate windows
for each new feature structure - a very bad idea with a reasonable number of
lexical rules.  A couple of years ago, I changed it so it produced a summary of
applications in a window with the format `lex-d + rule (+ rule)* = new orth'.
It applied recursively and was controlled only by
*maximal-lex-rule-applications*.  But this is also a bad idea for grammars such
as the current ERG, which now have a rather large fanout of punctuation rules
given that *maximal-lex-rule-applications* is set to 7 by default (and I
believe that's fine for applying the morphology in the usual way).  So the
interface now does not attempt recursive application, but the user can click on
a result and manually call `Apply all lex rules' again, and can repeat this as
often as desired. 

Other changes checked in are interim changes to the algebra code, which I
started working on last January but didn't get to a point where it was worth
enabling.  This is intended to display MRSs for nodes in a parse tree in the
algebra format - see Copestake et al Toulouse ACL paper - and allows one to
check that the algebra is obeyed.  I am returning to it and attempting to make
this work with non-trivial grammars.  I will announce it if I can get it to
work with the ERG, but otherwise won't bother notifying this list of further
changes to it. Meanwhile, I do not believe anyone should be inconvenienced by
the various updates to MRS code but let me know if anything new breaks ...