Rework resolver (#489)

* Rework IR and resolver to use nested lookup tables
* Integrate types into IR
* Make components prefer IR, slimmed down AST
* Implement `export *`
* Add `@lazy` annotation and remove `--noTreeShaking`
* Add `@start` annotation and remove magic `main`
* Related refactoring, cleanup and docs

tests/compiler/typealias.optimized.wat

@@ -3,14 +3,14 @@
  (type $_ (func))
  (memory $0 0)
  (table $0 1 funcref)
- (elem (i32.const 0) $start)
+ (elem (i32.const 0) $null)
  (export "memory" (memory $0))
  (export "table" (table $0))
  (export "alias" (func $typealias/alias))
  (func $typealias/alias (; 0 ;) (type $ii) (param $0 i32) (result i32)
   local.get $0
  )
- (func $start (; 1 ;) (type $_)
+ (func $null (; 1 ;) (type $_)
   nop
  )
 )