sandr Infinite Loops Prevented, Matches Like rex - Caveat

In version 7 and later, the Vortex <sandr> statement does not infinite-loop on expressions that match an empty string (e.g. ".,2"). Also, <sandr> now searches for an expression consistent with how <rex> does. For example, this means that start/end of buffer anchor sub-expressions (e.g. ">>=") are now respected properly.