~mna/snow unlisted

snow/pkg/parser/testdata/let_infer.snow.want -rw-r--r-- 95 bytes
Merge branch 'wip-group-var-let'
pkg/parser: fix tests with new var groups
pkg: move packages down one level
big refactor of compiler package into sub-packages
pkg/compiler: parse function attributes
test some invalid cases
pkg/compiler: more parser tests