remove dangerous r parameter to rm command in make clean target
add packed tag storage and PBF output support
string deduplication with a function to create an OSMPBF string table
string tables and tags in pbf writer.

also:
fixed nasty problem with elements that have zero tags.
now they should all point to tag file position 0, which contains a zero-length tag list.
fixed lat/lon coordinates (multiplier was wrong in pbf)
inline documentation rewrite. remove historgram code. check for way block overruns.
track 32-bit indexes that overflow, requiring ID space segmentation.

generalize output for things other than bytes, and use proper Ki Mi Gi suffixes.
check if has stop times for trip