new keywords and new features for old keywords

keyword	meaning	range	default	type	remarks
bmt_precession	compute the depolarization due to BMT precession	0, 1	0	integer
cuts_from_loaded_beam	calculate grid cuts from actually loaded beam	0,1	0	int	if load_beam = 1; beam supposed to be rather gaussian
cut_x_factor	value of cut_x in units of sigma_x	0., infinity	3.0	double	cut_x = cut_x_factor*sigma_x
cut_y_factor	value of cut_y in units of sigma_y	0., infinity	3.0	double	cut_y = cut_y_factor*sigma_y
cut_z_factor	value of cut_z in units of sigma_z	0., infinity	3.0	double	cut_z = cut_z_factor*sigma_z
do_bhabhas	bhabha treatment	0, 2	0	int	1 : reading bhabha.ini only, 2 : reading both bhabha.ini and bhabha_photon.ini
do_dump		0, 1	0	int	dump particles and photons each step dump files are named b1.n, b2.n for particles and bp1.N, bp2.n for photons (n = number of the step) (see release note 1.0.6 )
dump_particle		0, infinity	1	int	frequency of particle dump (see release note 1.0.6 )
dump_step		0, infinity	1	int	frequency of slice dump (see release note 1.0.6 )
load_beam	loading beams from electron.ini and positron.ini files	0 or 3 (PLACET)	0	int
polar_x		0., 1.	0.	double	effective only if bmt_precession
polar_y	components of the initial polarization vector	0., 1.	0.	double	see release note 1.0.6
polar_z		0., 1.	1.	double	for use
rndm_seed	value of the seed for random generation	0, infinity	0	long int
store_secondaries1	storing initial and final secondaries (pairs, bhabhas, compton...)	0, 1	0	int
track_secondaries2	tracking of secondaries (pairs, bhabhas, compton...)	0, 1	0	int
ST_spin_flip	compute the depolarization due to Sokolov-Ternov spin flip, in beamstrahlung	0, 1	0	integer	bmt_precession = 1 is mandatory
alpha_x, beta_x, alpha_y, beta_y	twiss parameters (beam emittance)	infinity	0	double
beam_crossing_angle	presence of a crossing angle between the two beams	0,1	0	int	without polarization
crossing_angle_value	value of crossing angle (degrees)	0,infinity	0	double	active only when beam_crossing_angle=1

1 replaces old keyword store_pairs; output files : secondaries0.dat and secondaries.dat

2 replaces old keyword track_pairs, output file : secondaries.dat (in place of pairs.dat)