parsing and writing of textual numeric data files

Changes for 2.004000

• Fix strict separator logic (no fuzzy whitespace on separators when strict parsing is in effect).
• Fix txdfilter --headlines to do what it was supposed to do.
• Add txdcontract --stats.
• Add txdhistogram --cumulative and --binpoints.
• Add ranges to txdcolumns.
• Add txdinfo --rows.
• Add txdfilter --index.
• Add txdcolumns --invert.
• Add txdrecycle --smother.
• Add min and max column to txdstatistics output.