Product: FieldMinMax message field
Product: improved collaborate method
Integer: refine, extract implementation for Bitfield, Interval and Set
Array*.accuracy: return 0.f instead of fail
In IntegerInterval, if top is set, the values are set to minimum and maximum values. Also, test for top tests these values as well (so if operation results in all the values, top is detected).
Fixes #175.
Merge branch 'rp-collaborate'

Conflicts:
	lib/ArraySingleItem.cpp
	tests/CMakeLists.txt
	tests/ProductVectorTest.cpp