*: add/fix godoc comments to satisfy golint

Fixes things like:
 * exported type/method/function X should have comment or be unexported
 * comment on exported type/method/function X should be of the form "X ..."
   (with optional leading article)

Refs. #213.

pkg/vm/vm.go

@@ -133,6 +133,7 @@ func (v *VM) LoadFile(path string) error {
 	return nil
 }
 
+// Load initializes the VM with the program given.
 func (v *VM) Load(prog []byte) {
 	// clear all stacks, it could be a reload.
 	v.istack.Clear()