correction: some relations were incomplete in special cases, e.g.
a restriction relation R1 that is completely located in tile 1,
but contains a way W which belongs to another restriction 
relation R2 that is also written to tile 2. 
When this happens, the way W is written
to tiles 1 + 2 and because of that the relation R1 was also
written to tiles 1 + 2.
The correction makes sure that relations which should be complete
are not also written to tiles in which they are not complete.
This increases memory requirements a little bit and reduces 
output file sizes a little bit.

git-svn-id: http://svn.mkgmap.org.uk/splitter/trunk@316 838fabe5-b1a8-4b81-9896-7a84386980e9