PLCgen: Errors with timers in TIA portal

Using the following CIF-model of a timer Test.cif we generated PLC-code Test_s7_300.zip to be used on the HIL-setup with a Siemens S7-300 PLC. Loading the PLC-code yielded in several errors:

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In the end it was not possible for us to implement a timer on the PLC. Since our lock-model contains several timers, this issue needs to be fixed with priority.

Addresses #679 Addresses #798 (closed)