Request for Code review: involving the regex optimizer and trickyfolds

I have pushed to a branch

remotes/origin/khw/tricky

code that attempts to fix the remaining problems involving 
multi-character folds outside [bracketed char classes].  (That is, those 
problems that can be fixed without a complete overhaul of Perls regex 
handling.)

These have come to be known as the tricky folds.  Making these changes 
required some changes to the dreaded regex optimizer.  I am leery of 
doing this, so tried to make the changes as minimal as possible, 
paralleling other code when possible.

I am hoping that someone at least semi-familiar with the optimizer would 
look at these patches.  Failing that, I'll push to blead eventually, and 
let the cruel world determine if this works or not.

The trie construction fails on these so I bypass it for these cases.

• Request for Code review: involving the regex optimizer and trickyfolds by Karl Williamson