Improved Ebel support
Added code for Boone 1661

Based on code found in
http://ftp.aip.org/epaps/medical_phys/E-MPHYA-24-1661/
and published in J. Boone and J. Seibert. An accurate method for
computer-generating tungsten anode x-ray spectra from 30 to 140 kv.
Medical physics, 24:1661, 1997.
More work... doesnt compile!
Fixed compile errors

To be tested
more work

difference between both boone models to be investigated
Merge branch 'bugfixes' into boone

Conflicts:
	bin/Makefile.am
typo fix
Imported Piernicola's work
Merge branch 'master' into boone
small change
results confirmed

although they differ considerably from Boone, the characteristic line
intensities seem to correspond to the reference values in Ebel 1999
Merge branch 'boone'