v0.7.3

Fixes:

• Fix overlapping edits in the formatter, hopefully making it idempotent (see #160);
• Fix formatter crashing the language server (see #161);
• Avoid unnecessary typechecking when semantics of a file has not changed (see #159);
• Stop typechecking after the first parse error (avoid invalid cache) (see 68ab0b4);

Other:

• Add unit tests for the formatter (see #157);