consolidate filter_table source code
bug popping in ktable

- off by one bug in count_coumns
- Use tab->cols everywhere it should be -- wasnt broken, but may prevent
  bugs in future
add wide test table
many changes to dist.c

- fix bugs w/ stdin /stdout opening
- add -M option for a thresholded manhattan distance
- misc other small changes and bug fixes

BUGS:
- there's still a bug in the calculation of canberra distances
  sometimes. Will sort this as I have time