reduce OSADamerau–Levenshtein space complexity from O(m*n) to O(3 * min(m*n))

[tang-hi]

Hi,this is the pr for issue.
I run the benchmark on OSADamerauLevenshtein.
Here is the result.

name	before	after	alloc_before	alloc_after
sameLengthStringInput	3389 ns/op	2416 ns/op	23 allocs/op	4 allocs/op
pneumonoultramicroscopi	15462 ns/op	10253 ns/op	51 allocs/op	8 allocs/op
こにんちこにんちこに	4027 ns/op	3342 ns/op	18 allocs/op	4 allocs/op
I_love_horror_movi	4282 ns/op	3073 ns/op	22 allocs/op	4 allocs/op

[hbollon]

What an amazing improvement! Thanks a lot for your work!
All tests are successful so I didn't see any reasons to don't merge that 😉

[tang-hi]

What an amazing improvement! Thanks a lot for your work! All tests are successful so I didn't see any reasons to don't merge that 😉

thanks