Version 0.53 released

[Jonathan Rees <Rees at YALE>]

I just released version 0.53.  A few minor bugs fixed.  A preliminary
version of a new routine, "GC", is there, but it hasn't been thoroughly
tested.  Its purpose is to reclaim unused storage.  Its main drawback at
the moment is that it blows up the SECOND time you call it.  Hopefully
this will be fixed shortly.

It does a LOT of metering and redundant error-checking, and of course
the compiler's code generator needs a lot of work, so it's a lot slower
than it ought to be.  And it probably prints out more statistics and
debugging info than you'd like to know (but you can set *GC-DEBUG?* to
() if you want).  So I wouldn't say that it's "released".  I'll let you
know when it's in better shape.

Report problems.