Revert "Adapt to format changes in floating point value printing."

This reverts commit a15ef54f.

This is the only way not to confuse the diagnostics engine of upgraded clang.

Also, this gives us a few advantages:
  * We can compare more precisely the source locations of diagnostics;
  * We can merge the code completion code path which works with file entries;
  * We can rely better when specifying //expected-note-s in different files.

Prevents possibility of last element referencing now invalid first element.

Various fixes based on comments after second round.

New printValue() integration (printing unified through overloading of printValue() function and template resolution).
Modified tests to conform to the new prints.

Dump cling::Value within setNoAlloc routines because this is its lifespan,
otherwise gets deleted if nobody requested it. I.e it was created only for
value printing purposes.

Dump cling::Value outside setWithAlloc because the actual value is not put inside
until the call to ::new finishes, thus we need to do it outside, i.e in EvaluateInternal.

Switch on the ValueExtraction synthesizer even when 'just' value printing. We
depend on it. Must be factored out properly in one class.

Stop attaching the value printing template magic, which didn't work in some cases.

Update the ref file, because now there is better type information.

Adapt the user-defined printout functions (TDatime).

When variadic return stmt doesn't have a return value, invalidate the calculation of the last expr for evaluation.

In the same cases we still need to synthesize the setValueNoAlloc, to initialize
the cling::Value to void.

Still missing: arrays incl arrays of objects.

This is actually an improvement in newest llvm. In that case we don't need
to run the test twice.

Use reg expr, because when building cling standalone we should still get _Bool.

When we dectect that the last expression is a record type and is not
a temporary, we now return it by reference, hence avoiding an unnecessary
and sometimes impossible (cout) copy.   If it is a temporary we still
return a 'copy'.