New syntax and parser.

[CathalMullan]

• [x] Update GitLab tests.
• [x] Add proper error messages to new enum.
• [x] Rethink allowed characters in parameter names.
• [x] Refresh docs (collapse trailing slash into optional group).
• [x] Changelog entry.
• [x] Tidy, document new parser code.

This syntax is very similar to Rails now, so maybe we should consider matching behaviour?

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 98.66844% with 10 lines in your changes missing coverage. Please review.

:white_check_mark: All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/parser.rs	98.78%	6 Missing and 1 partial :warning:
src/router.rs	90.47%	0 Missing and 2 partials :warning:
src/node/delete.rs	85.71%	1 Missing :warning:

Files with missing lines	Coverage Δ
src/errors/delete.rs	86.66% <100.00%> (ø)
src/errors/insert.rs	92.85% <100.00%> (ø)
src/errors/route.rs	100.00% <100.00%> (ø)
src/lib.rs	66.66% <ø> (ø)
src/node/insert.rs	93.79% <100.00%> (-0.09%)	:arrow_down:
src/node/delete.rs	79.50% <85.71%> (-0.50%)	:arrow_down:
src/router.rs	85.39% <90.47%> (-0.90%)	:arrow_down:
src/parser.rs	98.87% <98.78%> (+1.52%)	:arrow_up:

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #162 will not alter performance

_{Comparing 160-replace-adhoc-parser-with-grammar-based-parser (90d135c) with main (6b7deff)}

Summary

✅ 18 untouched benchmarks

⁉️ 1 dropped benchmarks

:warning: Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	160-replace-adhoc-parser-with-grammar-based-parser	Change
⁉️	gitlab delete benchmarks/wayfind	7 s	N/A	N/A