* Added progress reporting to binary operations
* Some doxygen fixes

Example improvements in binary operation speed, based on 10k Merlin spectra (old values in brackets).
           Windows     Linux(s1)
Plus       0.9 (4.5)   1.4 (6.8) seconds
Minus      1.0 (4.3)   1.4 (7.9) seconds
Multiply   0.8 (4.0)   1.2 (6.6) seconds
Divide     4.1 (7.9)   1.9 (6.6) seconds

Re #509.