Added options to exclude building Examples, Tutorials and Unit Tests.

Not building fpsviewer or Tutorial5 without Tinia_DESKTOP, since then no QT.

Fixes #40 and #38 

Timings from test runs
everything
real    1m12.905s
user    8m48.177s
sys     0m35.282s

all except desktop
real    0m30.322s
user    3m10.892s
sys     0m11.821s

server& unit tests
real    0m22.773s
user    2m12.992s
sys     0m8.349s

only server
real    0m19.070s
user    1m28.302s
sys     0m5.828s