Use HTTPS clone URL in README.
Allow same-level layout blocks.
Change quantifier syntax.

Universal quantifiers now use the "for all" sign (∀), or the at sign (@)
as an ASCII approximation, rather than curly braces with commas. Stack
variables use a postfix horizontal ellipsis (…) or ASCII triple dot
(...) rather than a prefix dot. Vector accessors now use dot (.) instead
of at (@) in order to avoid confusion. Range operators now use dashes
instead of dots (– for .. and — for ...) or their ASCII approximations
(-- and --- respectively).
Allow polymorphic UDTs and matches with closures.

Type parameters are specified after the type name using the universal
quantifier symbol. Branches of 'match' expressions are now treated as
closures so that they correctly capture locals from enclosing scopes.
Allow matching on UDTs in interactive mode.