[win] [test] DataSet::testValueIO change naming of value dsets

This fixes the test on window.
Merge pull request #140 from gicmo/win32_testfix

[win] [test] DataSet::testValueIO change naming of value dsets
new InvalidUnitException
Property::unit checks for SI units, add testProperty::testUnit
moved unit checks and validation to Property.hpp
enabled unit checking in DataArray
implement SimpleTag = and << operators
fixed wrongly thrown runtime exception in SimpleTagHDF5.addReference()
Added TestSimpleTag. Fixed deleter bugs in units and extents, units
are ensured to be SI units.
unit checking enabled in Dimensions, unit test stub
fixed bug in RangeDimension copy assignment operator
unit checking in Dimensions enabled (restricted to SI units)

this restriction must go at some point. for now only "easily" scalable
units are supported.
new TestDimensions
restricted unit test in SimpleTag to atomic SI units.
Rename InvalidUnitException to InvalidUnit
Merge pull request #142 from jgrewe/unit_checking

Unit checking validation and SimpleTag tests

SimpeTag tests were added (part of issue #25)
Unit checking is issue  #95
Updated SimpleTag & DataTag to have only "hasReference" & "removeReference" with "const string &id" parameter.
Fixed TestSimpleTag to use only "const string &id" version of "hasReference" & "removeReference"
Merge pull request #144 from balint42/fix_getter-setter

Final (alpha) fix of getter-setter patterns
Fixed all entity-handling setters to unset field or throw exception if empty entity passed.

The following setters are affected:

EntityWithMetadata::metadata 	(optional => unset field)
DataTag::extents		(optional => unset field)
DataTag::position 		(obligatory => throw runtime error)
Representation::data		(obligatory => throw runtime error)
Section::link			(optional => unset field)

Adressing issue #89