Work around 64bit id problem
Removed experimental simplification code.

Simplification should be solved outside this program. And it didn't work
anyway.
Fix for 64bit ids for osmcoastline_ways
Add the number of intersections between coastline segments to the warnings
Improve reporting of warnings and errors.

It is somewhat difficult to say which problems should be reported as warnings
and which as errors. This is a bit better than what we had before, but we'll
probably need a lot more experience with real world data to see how to do
this.
More than 500 warnings make an error