Use CSE logger to log progress

[kyllingstad]

This finally closes issue #6.

Here is what the output (or lack thereof) looks like now:

> cse run-single cse-core\test\data\ssp\demo\KnuckleBoomCrane.fmu
> cse run-single cse-core\test\data\ssp\demo\KnuckleBoomCrane.fmu --log-level=info
info: [FMI Library: FMILIB] Loading 'win64' binary with 'default' platform types
info: 10% complete, t=0.100000
info: 20% complete, t=0.200000
info: 30% complete, t=0.300000
info: 40% complete, t=0.400000
info: 50% complete, t=0.500000
info: 60% complete, t=0.600000
info: 70% complete, t=0.700000
info: 80% complete, t=0.800000
info: 90% complete, t=0.900000
info: 100% complete, t=1.000000

Note, this is not a fix for issue #12. I'll add a new switch for producing machine-readable output. This is for the user.