remove include or observer.hpp from radiation plugin
rename all observer.hpp to observer.param
add observer.param to default param loader
remove unnecessary code
add doxygen and rename index

add doxygen documentation
rename index parameter
add doxygen and rename index
make observer.param same as in bunch example
ad doxygen and rename index
comment computation of angles
copy comments from bunch example
add comments to KHI
extend comments
copy extended comments from bunch example
add extended documentation
add missing newline
extend default description
adjust default radiationConfig to work with 16x16 detector array
remove whitespace and fix typo
correct default setup
rename N_theta -> N_observers