[mkgmap-dev] [Patch v1] check length in substring style function

Hi all, the discussion about offsets in the mixed-index branch rang a bell: I forgot to answer this post from gbbickerton: "May i suggest that a test is made to check that the string is long enough before applying this filter otherwise an exception occurs .It would be unsafe to use this filter in any style without such a test. " Attached is a small patch that implements these plausibility checks. @gbbickerton: I noticed that you use substring:1:14 which removes the 1st character as counting starts with 0. If nobody complains I'll commit this on thursday. Gerd