Stable-ish

This release:

• Fixed an issue that sometimes prevented compilation on windows.

• Removes the positions_and_score() function. Instead, positions returns the indices and the score, i.e.

  idx, score = positions("ab", "ab") -- {1, 2}, inf
  idx = positions("ab", "ab")        -- {1, 2}

• Rather than picking the os-dependent path separator (/ or \), I just use both. Windows devs in particular will see both formats.

I don't anticipate any more changes to the API, just additions.