1.0.29.53: some LOAD-TIME-VALUE smartness

1.0.29.53: some LOAD-TIME-VALUE smartness

* Implicit READ-ONLY-P for obviously immutable values.

* Annotate the result with a derived type -- in practice
  the obvious declarared type of the function, if any.

* In the test suite organize compiler tests a bit:

  ** compiler-test-util.lisp has some general-purpose
     tools for determining if the compiled code passes muster.

  ** Move some pure tests from compiler.impure.lisp to the pure
     file: they were in the impure file because they defined
     utils which are now in the COMPILER-TEST-UTIL (aka CUA)
     package.