Fixed issues regarding function and rule references

Change-Id: I854b147a6776e23f603d0d47e11b7f3b4f16afee
Signed-off-by: mstegmaier <michael-1.stegmaier@uni-ulm.de>
Minor fix for undefined identifier warnings
environment variables can have arguments now

Change-Id: Ic8199e6f01ace9e338a7d6a2d0c35268a6fa4fa3
Signed-off-by: mstegmaier <michael-1.stegmaier@uni-ulm.de>
Merge branch 'master' into coreasm-compiler