This release fixes a number of bugs introduced with the switch
to libosmium and brings a couple of improvements in the
build system.

Changes include

- memory for caches and flatnode storage is freed earlier, leaving
  more RAM to Postgresql during indexing

- extend web Mercator to 89.99 latitude again, reducing broken polygons

- skip objects with no tags during initial import, improving
  performance during first import stage

- support LuaJIT for faster processing of Lua tag transforms

- update to libosmium 2.14

- windows builds for 32bit are now provided via Appveyor

- bug fixes for tile expiry

libosmium no longer ships with protozero since version 2.14. So
protozero is now seperately included in the contrib/ directory.
As with libosmium it is possible to switch to an externally
supplied library with cmake.