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/bool.optimized.wat

@@ -16,7 +16,7 @@
  (export "memory" (memory $0))
  (export "table" (table $0))
  (start $start)
- (func $start (; 1 ;) (type $_)
+ (func $start:bool (; 1 ;) (type $_)
   global.get $bool/i
   i32.const 0
   i32.ne
@@ -109,7 +109,10 @@
    unreachable
   end
  )
- (func $null (; 2 ;) (type $_)
+ (func $start (; 2 ;) (type $_)
+  call $start:bool
+ )
+ (func $null (; 3 ;) (type $_)
   nop
  )
 )