add default source limit 2100eV
ensure the source selection correct at start based on sequence file, and
excitation energy is upto date
refactor total steps and time calculation into a static method so it can
be shared by both views
add logger
add logger and implement default selection at file opening.
correct spelling mistake
Initialise sequence parameters and total steps and total time in
sequence table viewre.
add new, open save action on sequence
rename region in model to regions as it return a list of regions and
refactor code to remove unnecessary boolean input parameter as we
separated create sequence from get sequence.
change MessageBox to MessageDialog
change region to regions as it returns a list of region in model