Helper function used by nhgis() to read downloaded and unzipped codebook files obtained from NHGIS.org,
for US Census Bureau data from the American Community Survey (ACS).
Usage
nhgisreadcodebook(codebookfile, folder = getwd())See also
nhgis() which uses this, nhgisread() for reading datafiles, get.acs(), get.datafile.prefix(), datafile(), geofile(), get.zipfile.prefix()