Improve error detection

Improve error detection

Continued refinement and improvements to the error messages emitted when the user makes a mistake when writing Technique, especially around code blocks and variable bindings.

• Improve error detection and messages by @istathar in #81
• Fix syntax highlighting in formatting and rendering by @istathar in #84
• Update lsp-types dependency by @istathar in #85

Initial README

Long overdue, add a top-level README to the repository, along with the prototype examples we've been using all along to develop and test the parser and formatter.

• Initial README for compiler by @istathar in #83

Full Changelog: v0.4.4...v0.4.5