Fix build warning/error (gcc 4.2.1 on OSX, release mode).
Revert "Improve 'for' loops performance, closes #3303"

This reverts commit 9c00f223adc25d489afc5c3d21ca08ed2e922b03 which breaks
the charts module:

bar_chart.xl:
345            // Show x-label below chart
346            for I in 0..chart_xticks loop
347                locally
348                    translatex L * I

Conflicts:
	xlr/symbols.cpp
An additional optimization that works around #3327, fixes #3327

The problem appears with expression
    exp(1) * time

The problem goes away without the parentheses, although I see nothing wrong
with the code generated with the parentheses, just that it's a bit less
efficient because it does an additional type check that is useless.
That being said, the less efficient code causes LLVM to call into an 
unreachable block (which in itself is rather strange).
Add boolean to text conversion. Closes #3329.
Evaluate blocks without copying possibly null pointers, fixes #3327

We were starting the evaluation of blocks by copying the LLVM value
associated to the block into its child. But often, the child is where the
evaluation happens, and the block itself has been NULL-initialized.
We may end up with a NULL-deref. In the case of #3327, the optimizer was
smart enough to figure out that null-deref statically, so it replaced it
with a bizarre llvm.trap.

Lesson learned: seeing llvm.trap in the code means LLVM detected a NULL-deref.

Also removed the now useless block evaluation routines from basics.tbl
Merge branch 'master' of io.taodyne.com:~ddd/Work/xlr
Merge branch 'master' of ssh://io.taodyne.com/~jerome/Work/xlr
Merge branch 'master' of ssh://io.taodyne.com/~jerome/Work/xlr
CompileActions::Rewrites: do not assume return type in case of runtime error. Fixes #3345.
Fix possible NULL pointer dereference.

Found when reading code.
Improve reporting of divide-by-zero errors, closes #3380
Remove build error with LLVM warning on ErrorNameOf, closes #3381
Merge branch 'master' of ssh://io.taodyne.com/~ddd/RedmineProjects/xlr
Make tests more robust in environments with spaces in names, refs #3410 @30m
Fix build error on Windows, closes #3416 @1.5h
Merge branch 'master' of marypuce.local:Work/tao/tao/xlr into HEAD
Minor changes in the documentation
Added new path for serialized form
Merge branch 'master' of marypuce.local:Work/tao/tao/xlr into HEAD
Fixed name of executable for Windows, closes #3416 @25m