sais breaks if string starts with \0

[faassen]

I noticed that if you try to build a sais (and thus fmindex) with a string that starts with \0 things break. I figured a way around this in my code, but I wanted to leave this report here.

[faassen]

It would be nice to support this as it would let me write efficient starts with, ends with and equals searches. That is, if I want to look for the text "foo", "\0foo" would look for starts with, "foo\0" would look for ends with, and "\0foo\0" would look for exact identity. If the whole text cannot start with \0, then the starts with and equals searches cannot be implemented this way, as there would be no preceding \0.