WASM: Implement wasm-native strings part 1

There are several changes here but they all required for at least one test to pass.
- Implemented String class and several utility functions using built-in CharArray
- Added new constant memory segment to hold string literals and required funcs to work with them
- Added very crude mostly incorrect rudimentary ability to pass strings back to javascript

.idea/dictionaries/igor.xml

@@ -1,6 +1,7 @@
 <component name="ProjectDictionaryState">
   <dictionary name="igor">
     <words>
+      <w>addr</w>
       <w>descr</w>
       <w>exprs</w>
     </words>