Add methods to calculate the distance from a region

[MattBlissett]

Four commits:

• The first changes shorts to integers to allow using shapefiles with a larger number of regions
• The second reads the .cpg file (if it exists) to determine the character encoding of the shapefile's databases
• The third and fourth add the possibility to calculate if a point is within a particular distance of a region (including accounting for holes, area within holes etc).

I've compared the result to https://github.com/gbif/geocode (specifically, https://github.com/gbif/geocode/blob/master/geocode-ws/src/test/java/org/gbif/geocode/ws/service/impl/ShapefilesVsPostgisComparisonIT.java) and haven't found any differences. The Java version is considerably faster, mostly as it avoids the round trip to the database.