Build mkgmap/splitter #10.1

add option --ignore-bounds-tags with a default value false By default splitter prefers the bounds given with the first bounds tag found in the input file(s). With option --ignore-bounds-tags it ignores all these tags and uses the bbox calculated by the nodes found in the first input file. Some input files contain wrong or at least strange bounds tags, for example an extract of Alaska produced around 2014-10-18 contained the invalid bbox <bounds minlat="49.8089" minlon="-179.9532" maxlat="73.79794" maxlon="180.0005"/> Another one produced 2016-03-26 contains <bounds minlat="49.8089" minlon="-179.9532" maxlat="73.79794" maxlon="179.9999"/> which is still far too large. On the other hand, the extract for Bremen (Germany) contains <bounds minlat="53.01034" minlon="8.480959" maxlat="53.61063" maxlon="8.991268"/> while the nodes in the file covers a much larger bbox: lon min: 7.8917689 lon max: 9.1518468 lat min: 52.8264462 lat max: 54.1797522