tabconv (no version)
Converts files created with 8sp tabs to 4sp tabs and back.
Only tabs and spaces which begin lines are converted.
Examples:
  forward:
    4 spaces go into 1 tab
    1 tab goes into 2 tabs;
    8 spaces, 1 tab go into 4 tabs
    7 spaces, 1 tab go into 2 tabs
    1 tab, 5 spaces go into 3 tabs, 1 space
  backward:
    8 spaces go into 1 tab
    20 spaces go into 2 tabs, 2 spaces
    2 tabs go into 1 tab
    3 tabs go into 1 tab, 4 spaces
... etc
Bugs:
If a file mask specified, it works only in current directory (lazy to fix).

By SM