move most code from method_compiler to builder

rather use builder in two ways, than sometimes compiler and sometimes
builder
Also makes it possible to reuse builtin code in mom’s to_risc, as both
use builder. The builtin code by directly adding to compiler, the mom
code not.

lib/mom/instruction/dynamic_call.rb

@@ -2,12 +2,12 @@ module Mom
 
   # A dynamic call calls a method at runtime. This off course implies that we don't know the
   # method at compile time and so must "find" it. Resolving, or finding the method, is a
-  # a seperate step though, and here we assume that we know this Method instance.
+  # a seperate instruction though, and here we assume that we know this Method instance.
   #
   # Both (to be called) Method instance and the type of receiver are stored as
   # variables here. The type is used to check before calling.
   #
-  # Setting up the method is not part of the instructions scope. That setup
+  # Setting up the method is not part of this instructions scope. That setup
   # includes the type check and any necccessay method resolution.
   # See vool send statement
   #