new egg: phosphate

Phosphate is a parser-combinator library with error recovery and dynamic 
state with better tail-recursion properties than `parameterize` in most 
implementations (no dynamic-wind).

Compared to comparse parsers, Phosphate parsers are more verbose and 
probably slower. However, Phosphate allows for flexible parsers that use 
continuations for error recovery, and exposes internals of the parser 
stream for flexibility.

release-info: https://florida.moe/phosphate/phosphate.release-info
wiki: https://wiki.call-cc.org/eggref/5/phosphate
git: https://codeberg.org/phm/phosphate

(The documentation file is 1800 lines long, I will port it to svnwiki 
format eventually.)

-- Peter McGoron