replace commented fprintf with DBG_CTX
add a column member to all Definitions

only the line is currently tracked, but report
a precise location, track also the column.
make the scanners fill in the column information

Only C scanner reports a correct column, while for
the other languages, a default value 1 is used.
track location for references and referencedby

The hash key is now the file location(file:line:column).
Later on, this key is used to provide the reference location
to the consumers(xmlgen and sqlite3gen)
xmlgen: add attribute 'column' for 'location' tag
xmlgen: add attributes atline,atcol,infile for 'references' tag
sqlite3gen: generate sqlite3