do not cache skipped nodes
removed unused code
fix race condition where leveldb is closed before the iterator

should solve assertion errors like:
db/version_set.cc:710: leveldb::VersionSet::~VersionSet(): Assertion `dummy_versions_.next_ == &dummy_versions_' failed
fix closing of nodes iter channel
remove skipped nodes before accessing first ID; skip empty node lists
transform nodes to mercator before limiting in reader
write replicationURL of last state in new state
removed unused code
add new Expireor interface
do not add prepared geometries to index
do not open OSM/DiffCache for each Update
add -quiet options to imposm3 diff
close OSM/DiffCache after update
refactored parallel parser
limit ways and relations as well

only cache ways if the first coord is cached, only cache relations
if the first member is cached.

we need to sync the read process so that we have all coords cached
before the first way gets checked for limitto.
make sure clipped geometries are DestroyedLayer
transform nodes before checking against limito in diff import
initialize coordsBunch map with capacity size
reuse freeNodes
set cache.BlockSizeK in KB not MB