Modify rtl testbench for post route simulation

[mkosunen]

Depends on https://github.com/TheSystemDevelopmentKit/thesdk/pull/47

Changes:

• Add vloglibfiles property which reads a list of external module files from thesdk global variable 'VLOGLIBFILE'.
• Add rtl_timeprecision to rtl
• Testbench timescale directive matches now the command line timescale argument.