[Ecls-list] Important fixes

[Juan Jose Garcia Ripoll]

Hi,

I have committed the following fixes, some of them very important. 
Please report if ECL fails to work properly.

+ TRUENAME always detects the existence of the file (M.G.)

+ EQUALP works now on hash tables (M.G.)

+ (PARSE-NAMESTRING "") no longer sets the version to :NEWEST (M.G.)

+ Circular structures are now properly detected in the pretty printer.

In particular the changes of the printer, due to the coexistence of two 
types of pretty printers, are a bit ugly and might reveal some further 
inconsistency. But at least now ECL does not hang when trying to print 
circular structures if *PRINT-CIRCLE* = T.

Juanjo