Length: wavelength - transmittance
XMLMockObjects: Fix usage of Length.
FormatTools: PositiveInteger becomes Length.

Conflicts:
	components/formats-api/src/loci/formats/FormatTools.java
Fix readers using PositiveInteger.
Length: wavelength - light sources
Fix unit test.
Fix Mock objects.
Merge pull request #13 from bpindelski/transmittance-wavelength

Length: wavelength - transmittance
Length: wavelength - emission and excitation
Length: well origin
Return length object.

To avoid conflict, I did not use import...
Use Length for plate well origin
Modify readers to support length quantity for wavelength.
Fix Channel wavelengths to use Length quantity
Merge pull request #14 from rleigh-dundee/units-length

Units: Length for plate well origin
Fix ICSReader
Fix duplicate imports
Merge pull request #16 from sbesson/units-length

Units length: channel wavelengths
Fix test-suite for channel wavelengths
Merge pull request #17 from sbesson/units-length

Fix test-suite for channel wavelengths