changes from 0.06 to 0.07
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* changed error handling if exec() fails to avoid problems with block eval
changes from 0.05 to 0.06
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* added filehandle duping to reset STD* filenos in the child process
changes from 0.04 to 0.05
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* fixed the order of filehandle processing in the child process
changes from 0.02 to 0.04
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* fixed tests for better taint-mode handling
changes from 0.01 to 0.02
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* documentation fixes