use go.tools/go/types + simplified pkg structure
more migration to go.tools/go/types
go-eval/pkg/eval -> go-eval
bridge: first stab at map
bridge: gofmt
test: disable known-to-fail tests
stmt: stubs for compileConstDecl
stmt: hard-code pre-conditions
type: remove Pos() from Type interface
all: updates for upstream go/types
world: cosmetics
world: properly catch non-implemented 'import foo'