[Ecls-list] One more fix

[Juan Jose Garcia Ripoll]

Another BIG fix:

* The compiler has a brand new set of data structures for representing 
forms, which keep track of where variables are used, parent forms, etc. 
These new structures are used to compute whether a function needs a 
lexical environment, whether this environment has to be stack allocated 
or a list, replacing variables with their values, etc.

For the last two months I have been keeping three branches of 
development: the standard ECL, a branch for improvements in the 
compiler, and another branch in which I host an improved interpreter.

Due to the excellent work of Michael the number of fixes to the standard 
branch is growing steadily ;-) and these branches are becoming a 
nightmare to maintain. Hence I decided to merge in the changes to the 
compiler right now.

This solves a number of errors in Paul's test suite, but ECL has not yet 
reached the desired stability under the random tester.

Regards,

Juanjo