merged branch fabpot/loop-errors (PR #927)

This PR was merged into the master branch.

Commits
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811dfad added a syntax error when using a loop variable that is not defined (closes #925)
aa15cae simplified code

Discussion
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added a syntax error when using a loop variable that is not defined

refs #925

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by stof at 2012-12-10T15:18:30Z

in the ifexpr, you should also check for ``loop.index`` & co as they are not yet incremented (and so cannot be used properly)

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by fabpot at 2012-12-10T20:07:08Z

@stof fixed