Performance issues/timeouts on some grammars

[tomtau]

Possibly related issues:

• https://github.com/pest-parser/pest/issues/675
• https://github.com/pest-parser/pest/issues/603
• https://github.com/pest-parser/pest/issues/571
• https://github.com/pest-parser/pest/issues/402
• https://github.com/pest-parser/pest/issues/279

Suggestions from @dragostis :

Ideally, the optimizer should be able to detect all exponential cases and have replacement rules for them. Maybe someone could take a look at egg and implement a simplified version of the grammar there so peephole optimizations can be more easily written?

plus more context on why packrat parsing wasn't used: https://github.com/pest-parser/pest/pull/684#issuecomment-1210310442