[Imports] Import US County data

[Mike N.]

I have obtained a set of road centerlines from a US county that has been 
published in the public domain.   I would like to use this to correct the 
OSM roads for that county, since the TIGER data was one of the "poor 
alignments" that we are so familiar with.   In addition, the road names have 
all been changed for E911 consistency.   This file is likely even newer than 
the 2010 TIGER centerlines.

  I have used Ian's shp-to-osm to begin looking at the data.

   1.   Does anyone have a rules file for a typical municipal road 
centerlines shape file conversion?     I started to develop this, but can't 
believe no one has done this before.
   2.   Is it good to preserve TIGER tags for untouched roadways, or just 
delete and replace them?   The geometry is so far off that it is easier to 
delete and replace.

  Usual import disclaimers -

  Any relations will be preserved.
  Any existing road alignment edits will be preserved (such as for 
interstates)
  Any existing attribution will be preserved (speed limits, traffic lights, 
etc)
  Corrected data will be manually stitched to existing data at borders or 
pre-edited roads.