Option to guarantee linear time with regards to input size, like re2 (ReDoS protection)

[Anton3]

We were choosing between re2 and CTRE. A much nicer constant factor of CRTE is much appreciated, but we had to choose re2, because CTRE has no option to protect against ReDoS (regex denial of service) and prohibit forms of syntax that involve backtracking. Please implement this option so that enterprise-scale code can rely on CTRE without the fear of ReDoS.

[hanickadot]

I'm currently quite busy with other priorities. If you want to speed it it up, please try to write a PR.