added source refs and renamed non modules to targets
Merge branch 'develop' into feature/math-mod
 missing files...
Typo
Load Modules in semantic definition
Removed unnecessary argument
Renamed file argument to be consistent
Feature: Modules can now be used

Modules can be defined in the program definition or any
node implementation. They create their implementation
dynamically.
I added a Math Module that translate an expression into a
implementation using atomics. Currently only Add and Constant
are supported.