Refactoring and cleanup of rtl.CodeGenerator.
Refactoring and cleanup of rtl.CodeGenerator.

 * Created a method for copy-pasted array-lookup address calculating
   code.
 * Extracted methods generateBinary and generateFunctionCall.
 * Deleted unecessary empty lines that didn't serve to group related
   lines of code.
 * Added comment explaining the complex behaviour of
   generateAssignment.

margnus1/micro-c,margnus1/micro-c