news + TODOs
add script tests for merging
document some more parameters
fixes for merge tool

improvements in help text
rename "auto" strategy to "preserve"
avoid overwriting of other keys into mergedKeys
do a get() first so that writing to mergedKeys will work
open 3x so that it will also work when everything is in the same
     mountpoint
only do output when -v (verbose) is selected
uniformly use ToolException in libtools

move exceptions to begin of file
document some parameters
add contract tutorial
add missing parts of contract in the spec
small change in Tutorial