Parses the PRO100 fixed-layout text formats (# Parts / # Materials).
UTF-8 with an optional leading BOM, TAB-separated, CRLF (or LF) lines. Each
data row begins with two empty fields (the leading \t\t); after dropping
them the positional columns are:
Furniture: name id c3 price c5 c6 c7
Materials: name id c3 price c5 unit